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Simulation driven design : An iterative approach for mechanical engineers with focus on modal analysisErlandsson, Andreas January 2015 (has links)
This thesis of 15 hp has been implemented at Halmstad University, in collaboration with Saab Dynamics in Linköping. Saab Dynamics is a company operating in the defence industry where competition is tough. This necessitates new ways to increase efficiency in the company, which is the basis for this thesis. Saab Dynamics wants to introduce simulation driven design. Since Saab Dynamics engineers have little experience of simulation, required a user methodology with clear guidelines. Due to lack of time, they chose to assign the task to students, which resulted in this thesis. The aim of the thesis is to develop a methodology in mechanical design, where the designer uses the FE analysis early in the design process to develop the structures' mechanical properties. The methodology should be seen as a guide and a source of information to enable an iterative approach with FE-analysis, which is the basis of simulation-driven design. The iterative process of simulation driven design, which can lead to reduced lead times and cost savings in the design process. The work was carried out by three students from the mechanical engineering program between December 2014 and May 2015. Because of the scale of the project, it has been carried out by a total of three students with individual focus areas. The work has followed a self-developed method and the project began with theoretical studies of the topic to get an understanding of what has been done and what research in simulation driven design. Then conducted an empirical study on the Saab Dynamics in Linköping, in order to increase understanding of how the design process looks like. Meanwhile, sustainable development and ethical aspects has been taken into account. Much time has been devoted to investigate the possibilities and limitations of 3D Experience, which is Dassault Systèmes latest platform for 3D modelling- and simulation software. 3D Experience is the software, the methodology is based on. This thesis has resulted in a methodology for simulating at the designer level that the project team in consultation with the supervisor at Saab Dynamics managed to adapt to the company's requirements.
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Evaluation of Energy-Optimizing Scheduling Algorithms for Streaming Computations on Massively Parallel Multicore Architectures / Evaluering av energioptimerande schemaläggningsalgoritmer för strömmande beräkningar på massivt parallella flerkärniga arkitekturerJanzén, Johan January 2014 (has links)
This thesis describes an environment to evaluate and compare static schedulers for real pipelined streaming applications on massively parallel architectures, such as Intel Single chip Cloud Computer (SCC), Adapteva Epiphany, and Tilera TILE-Gx series. The framework allows performance comparison of schedulers in their execution time, or the energy usage of static schedules with energy models and measurements on real platform. This thesis focuses on the implementation of a framework evaluating the energy consumption of such streaming applications on the SCC. The framework can run streaming applications, built as task collections, with static schedules including dynamic frequency scaling. Streams are handled by the framework with FIFO buffers, connected between tasks. We evaluate the framework by considering a pipelined mergesort implementation with different static schedules. The runtime is compared with the runtime of a previously published task based optimized mergesort implementation. The results show how much overhead the framework adds on to the streaming application. As a demonstration of the energy measuring capabilities, we schedule and analyze a Fast Fourier Transform application, and discuss the results. Future work may include quantitative comparative studies of a range of different static schedulers. This has, to our knowledge, not been done previously.
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Instrumentation Analysis: An Automated Method for Producing Numeric Abstractions of Heap-Manipulating ProgramsMagill, Stephen 29 November 2010 (has links)
A number of questions regarding programs involving heap-based data structures can be phrased as questions about numeric properties of those structures. A data structure traversal might terminate if the length of some path is eventually zero or a function to remove n elements from a collection may only be safe if the collection has size at least n.
In this thesis, we develop proof methods for reasoning about the connection between heap-manipulating programs and numeric programs. In addition, we develop an automatic method for producing numeric abstractions of heap-manipulating programs. These numeric abstractions are expressed as simple imperative programs over integer variables and have the feature that if a property holds of the numeric program, then it also holds of the original, heap-manipulating program. This is true for both safety and liveness. The abstraction procedure makes use of a shape analysis based on separation logic and has support for user-defined inductive data structures.
We also discuss a number of applications of this technique. Numeric abstractions, once obtained, can be analyzed with a variety of existing verification tools. Termination provers can be used to reason about termination of the numeric abstraction, and thus termination of the original program. Safety checkers can be used to reason about assertion safety. And bound inference tools can be used to obtain bounds on the values of program variables. With small changes to the program source, bounds analysis also allows the computation of symbolic bounds on memory use and computational complexity.
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The relationship between postural stability sway, balance, and injury in adolescent female soccer players in the eThekwini district of KwaZulu-NatalKoenig, Jean-Pierre 24 July 2014 (has links)
Submitted in partial compliance with the requirements for the Master of Technology: Chiropractic, Durban University of Technology, 2014. / Background: Poor balance is a risk factor for injury in adolescent sport including soccer. Despite the rapid growth in female adolescent soccer especially in South Africa, the association between balance and injury in this population has not been fully explored. This study aimed to determine the relationship between injury and balance. Static and dynamic balance was monitored as sway index (SI) and limits of stability direction control (LOSDC).
Objectives: The objectives of this study were to determine the body mass index of adolescent female soccer players; to determine the prevalence of injury in adolescent female soccer players; to determine static balance as revealed by the sway index (SI); to determine dynamic stability as revealed by limits of stability direction control (LOSDC) and to correlate body mass index (BMI) to sway index and limits of stability.
Method: Eighty adolescent female soccer players, between the ages of fourteen and eighteen, were recruited through convenience sampling from schools in the eThekwini district of KwaZulu-Natal. After obtaining informed consent and assent, participants completed questionnaires and were scheduled for the balance and BMI assessments. The objective data for each participant consisted of height, weight, Sway Index (SI) and Limits of Stability Direction Control (LOSDC) readings, measured using a stadiometer, electronic scale and Biodex Biosway Balance System (Biodex Medical Systems Inc., Shirley, New York) respectively. The subjective and objective data were analyzed using SPSS version 21.0 (SPSS Inc. Chicago, Ill, USA). Statistical tests included descriptive statistics using frequency and cross-tabulation. Inferential statistics using t-tests and Pearson’s correlations at a significance level of 0.05 was also incorporated. The testing of hypotheses was performed using Fisher’s Exact tests for nominal data and ordinal data. A p value of < 0.05 was considered as statistically significant. The statistical analysis also included Odds Ratio calculations.
Results: The mean body mass index of the injured participants was 23.54±3.56 kg/m2 and the mean body mass index of the uninjured participants was 23.00±4.63. Only 27.5% of the participants sustained an injury. Injured participants performed poorly on average in the SI assessment involving their eyes open when standing on a soft surface. The results were similar for the LOSDC in the overall, right, left, backward-right and backward-left directions. However, there were no significant correlations calculated. Significant relationships existed between BMI and the SI assessments in the injured participants which involved standing on a firm surface with their eyes open (p = 0.05), their eyes closed when also standing on a firm surface (p = 0.05), their eyes open when standing on a soft surface (p = 0.02), and their eyes closed when standing on a soft surface (p = 0.04). A significant relationship also existed between BMI and LOS right direction control (p = 0.02).
Conclusion: This research paper revealed that the body mass index as investigated in this study is similar to other studies involving female adolescents; soccer injury as investigated in this study is similar to other studies involving female adolescents; poor static and dynamic balance is not associated with injury in adolescent female soccer players and lastly, body mass index is linked to the balance of an individual.
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SOIL-WATER COUPLED FINITE DEFORMATION ANALYSIS BASED ON A RATE-TYPE EQUATION OF MOTION INCORPORATING THE SYS CAM-CLAY MODELNAKANO, MASAKI, ASAOKA, AKIRA, NODA, TOSHIHIRO 12 1900 (has links)
No description available.
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Delay Analysis of Digital Circuits Using Prony's MethodFu, Jingyi J.Y. 28 July 2011 (has links)
This thesis describes possible applications of Prony's method in timing analysis of digital circuits. Such applications include predicting the future shape of the waveform in DTA(Dynamic Timing Analysis) and delay look-up table in STA(Static Timing Analysis).
Given some equally spaced output values, the traditional Prony's method can be used to extract poles and residues of a linear system, i.e. to characterize a waveform using an exponential function. In this thesis, not only values but also equally spaced derivatives are tested. Still using same idea of the traditional Prony's method, poles and residues can also be extracted with those values and derivatives. The resultant poles and residues will be used to predict the output waveform in DTA analysis. The benefits brought by the using of derivatives include less simulation steps and less CPU time consuming than the regular constant step simulation.
As a matter of fact, the Prony's method can precisely approximate a complicated waveform. Such property can be applied for STA analysis. The Prony's approximation can be used to precisely record an output waveform, which is used as an entry of the look-up table of STA. Since the accuracy of STA analysis relies on the accuracy of the input and output waveform in the look-up table, the accuracy of the Prony's approach is promising.
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Decision support algorithms for power system and power electronic designHeidari, Maziar 10 September 2010 (has links)
The thesis introduces an approach for obtaining higher level decision support information using electromagnetic transient (EMT) simulation programs. In this approach, a suite of higher level driver programs (decision support tools) control the simulator to gain important information about the system being simulated. These tools conduct a sequence of simulation runs, in each of which the study parameters are carefully selected based on the observations of the earlier runs in the sequence. In this research two such tools have been developed in conjunction with the PSCAD/EMTDC electromagnetic transient simulation program. The first tool is an improved optimization algorithm, which is used for automatic optimization of the system parameters to achieve a desired performance. This algorithm improves the capabilities of the previously reported method of optimization-enabled electromagnetic transient simulation by using an enhanced gradient-based optimization algorithm with constraint handling techniques. In addition to allow handling of design problems with more than one objective the thesis proposes to augment the optimization tool with the technique of Pareto optimality. A sequence of optimization runs are conducted to obtain the Pareto frontier, which quantifies the tradeoffs between the design objectives. The frontier can be used by the designer for decision making process.
The second tool developed in this research helps the designer to study the effects of uncertainties in a design. By using a similar multiple-run approach this sensitivity analysis tool provides surrogate models of the system, which are simple mathematical functions that represent different aspects of the system performance. These models allow the designer to analyze the effects of uncertainties on system performance without having to conduct any further time-consuming EMT simulations. In this research it has been also proposed to add probabilistic analysis capabilities to the developed sensitivity analysis tool. Since probabilistic analysis of a system using conventional techniques (e.g. Monte-Carlo simulations) normally requires a large number of EMT simulation runs, using surrogate models instead of the actual simulation runs yields significant savings in terms of shortened simulation time. A number of examples have been used throughout the thesis to demonstrate the application and usefulness of the proposed tools.
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Spherical harmonic inductive detection coils and their use in dynamic pre-emphasis for magnetic resonance imagingEdler, Karl 13 September 2010 (has links)
The issue of eddy currents induced by the rapid switching of magnetic field gradients is a long-standing problem in magnetic resonance imaging. A new method for dealing with this problem is presented whereby spatial harmonic components of the magnetic field are continuously sensed, through their temporal rates of change, and corrected. In this way, the effects of the eddy currents on multiple spatial harmonic components of the magnetic field can be detected and corrections applied during the rise time of the gradients.
Sensing the temporal changes in each spatial harmonic is made possible with specially designed detection coils. However to make the design of these coils possible, general relationships between the spatial harmonics of the field, scalar potential, and vector potential are found within the quasi-static approximation. These relationships allow the vector potential to be found from the field – an inverse curl operation – and may be of use beyond the specific problem of detection coil design.
Using the detection coils as sensors, methods are developed for designing a negative feedback system to control the eddy current effects and optimizing that system with respect to image noise and distortion. The design methods are successfully tested in a series of proof-of-principle experiments which lead to a discussion of how to incorporate similar designs into an operational MRI.
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Application of VAX/VMS graphics for solving preliminary ship design problemsMcGowan, Gerald K. 12 1900 (has links)
Approved for public release; distribution is unlimited / The VAX/VMS UIS graphics library routines were used in the creation of a menu driven, interactive program which solves basic preliminary ship design problems. The program uses a menu with active mouse and keyboard to select options, enter data, and control program execution. At present, the program solves transverse and longitudinal static stability problems and predicts the effects of shifting weight in three planes. It also calculates the hydrodynamic derivatives for maneuvering performance and predicts the turning circle characteristics of the ship. Provisions for a hardcopy, detailed report are also included. Space has been allocated to include future program modules or user supplied programs.
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Hermes: A Targeted Fuzz Testing FrameworkShortt, Caleb James 12 March 2015 (has links)
The use of security assurance cases (security cases) to provide evidence-based
assurance of security properties in software is a young field in Software Engineering.
A security case uses evidence to argue that a particular claim is true. For example,
the highest-level claim may be that a given system is sufficiently secure, and it would
include sub claims to break that general claim down into more granular, and tangible,
items - such as evidence or other claims. Random negative testing (fuzz testing) is
used as evidence to support security cases and the assurance they provide. Many
current approaches apply fuzz testing to a target system for a given amount of time
due to resource constraints. This may leave entire sections of code untouched [60].
These results may be used as evidence in a security case but their quality varies
based on controllable variables, such as time, and uncontrollable variables, such as
the random paths chosen by the fuzz testing engine.
This thesis presents Hermes, a proof-of-concept fuzz testing framework that provides improved evidence for security cases by automatically targeting problem sections
in software and selectively fuzz tests them in a repeatable and timely manner. During
our experiments Hermes produced results with comparable target code coverage to
a full, exhaustive, fuzz test run while significantly reducing the test execution time
that is associated with an exhaustive fuzz test. These results provide a targeted piece
of evidence for security cases which can be audited and refined for further assurance.
Hermes' design allows it to be easily attached to continuous integration frameworks
where it can be executed in addition to other frameworks in a given test suite. / Graduate / 0984 / cshortt@uvic.ca
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