Дисертації з теми "Sensitivity to the method"
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1
Borggaard, Jeffrey T. "The sensitivity equation method for optimal design." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/38563.
Повний текст джерелаАнотація:
In this work, we introduce the Sensitivity Equation Method (SEM) as a method
for approximately solving infinite dimensional optimal design problems. The SEM
couples a trust-region/quasi-Newton optimization algorithm with gradient information
provided by apprOXimately solving the sensitivity equation for (design) sensitivities.
The sensitivity equation is (in the problems considered here) a partial differential
equation (POE) which describes the influence of a design parameter on the state of
the system. It is shown that obtaining design sensitivities from the sensitivity equation
has advantages over finite difference and semi-analytical methods in that there is no need to remesh or compute mesh sensitivities (even if the domain is parameter
dependent), the sensitivity equation is a linear POE for the sensitivities and can be
approximated in an efficient manner using the same approximation scheme used to
approximate the states.
The applicability of the SEM to shape optimization problems, where the state is
described by the Euler equations, is studied in detail. In particular, we prove convergence of the method for a one dimensional test problem. These results are used to speculate on the applicability of the method for more complex problems. Finally. we solve a two dimensional forebody simulator design problem (for use in wind tunnel experiments) using the SEM, which is shown to be a very efficient method for this problem.Ph. D.
2
Liu, Shaobin. "Continuum Sensitivity Method for Nonlinear Dynamic Aeroelasticity." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23282.
Повний текст джерелаАнотація:
In this dissertation, a continuum sensitivity method is developed for efficient and accurate computation of design derivatives for nonlinear aeroelastic structures subject to transientaerodynamic loads. The continuum sensitivity equations (CSE) are a set of linear partial
differential equations (PDEs) obtained by differentiating the original governing equations of
the physical system. The linear CSEs may be solved by using the same numerical method
used for the original analysis problem. The material (total) derivative, the local (partial)
derivative, and their relationship is introduced for shape sensitivity analysis. The CSEs are
often posed in terms of local derivatives (local form) for fluid applications and in terms of total
derivatives (total form) for structural applications. The local form CSE avoids computing
mesh sensitivity throughout the domain, as required by discrete analytic sensitivity methods.
The application of local form CSEs to built-up structures is investigated. The difficulty
of implementing local form CSEs for built-up structures due to the discontinuity of local
sensitivity variables is pointed out and a special treatment is introduced. The application
of the local form and the total form CSE methods to aeroelastic problems are compared.
Their advantages and disadvantages are discussed, based on their derivations, efficiency,
and accuracy. Under certain conditions, the total form continuum method is shown to be
equivalent to the analytic discrete method, after discretization, for systems governed by a
general second-order PDE. The advantage of the continuum sensitivity method is that less
information of the source code of the analysis solver is required. Verification examples are
solved for shape sensitivity of elastic, fluid and aeroelastic problems.
Ph. D.
3
Witzgall, Zachary F. "Parametric sensitivity analysis of microscrews." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4892.
Повний текст джерелаАнотація:
Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xi, 73 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 52-53).
4
Baidar, Binaya. "A sensitivity analysis of the Winter-Kennedy method." Licentiate thesis, Luleå tekniska universitet, Strömningslära och experimentell mekanik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70157.
Повний текст джерелаАнотація:
Hydropower is among the lowest-cost electrical energy sources due to its long lifespan and lower operation and maintenance cost. The hydro-mechanical components of hydropower plants generally last about four to five decades, then they are either overhauled or replaced. The major upgrades and refurbishments of the hydropower plants that are ongoing have also been motivated by the introduction of new rules and regulations, safety or environmentally friendly and improved turbine designs. Whatever are the drivers, the refurbishments are usually expected to increase efficiency, flexibility and more power from the plant. Efficiency measurement is usually performed after refurbishments. While it is relatively straightforward to measure efficiency in high head machines due to the availability of several code-accepted methods, similar measurements in low head plants remain a challenge. The main difficulty lies in the discharge/flow rate measurement. The reason is due to the continuously varying cross-section and short intake, as a result, the flow profile or parallel streamlines cannot be established. Among several relative methods, the Winter-Kennedy (WK) method is widely used to determine the step-up efficiency before and after refurbishment. The WK method is an index testing approach allowing to determine the on-cam relationship between blade and guide vane angles for Kaplan turbine as well. The method utilizes features of the flow physics in a curvilinear motion. A pair of pressure taps is placed at an inner and outer section of the spiral case (SC). The method relates discharge (Q) as Q=K(dP)^n, where K is usually called as the WK constant and n is the exponent whose value varies from 0.48 to 0.52. dP is the differential pressure from the pair of pressure taps placed on the SC. Although the method has very high repeatability, some discrepancies were noticed in previous studies. The reasons are often attributed to the change in local flow conditions due to the change in inflow conditions, corrosions, or change in geometry. Paper A is a review of the WK method, which includes the possible factors that can influence the WK method. Considering the possible factors, the aim of this thesis is to study the change in flow behavior and its impact on the coefficients. Therefore, a numerical model of a Kaplan turbine has been developed. The turbine model of Hölleforsen hydropower plant in Sweden was used in the study. The plant is considered as a low head with 27-m head and a discharge of 230 m3/s. The 1:11 scale model of the prototype is used as the numerical model in this study, which has 0.5 m runner diameter, 4.5 m head, 0.522 m3/s discharge and 595 rpm at its best efficiency point. A sensitivity analysis of the WK method has been performed with the help of CFD simulations. The numerical results are compared with the previously conducted experiment on the model. The study considers four different WK configurations at seven locations along the azimuthal direction. The simulations have been performed with different inlet boundary conditions (Paper B and Paper C) and different runner blade angles (Paper C). The CFD results show that the WK coefficients are sensitive to inlet conditions. The study also concludes that to limit the impact of a change in inflow conditions, runner blade angle on the coefficients, the more suitable WK locations are at the beginning of the SC with the inner pressure tap placed between stay vanes on the top wall.
5
Maree, A. J. "The inverse finite element method : sensitivity to measurement setup /." Link to the online version, 2005. http://hdl.handle.net/10019/1088.
Повний текст джерела
6
Maree, Abraham Jacobus. "The Inverse Finite Element Method: Sensitivity to Measurement Setup." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/2640.
Повний текст джерелаАнотація:
Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2005.In the inverse finite element method (iFEM), given a finite element model of a structure and imperfect displacement measurements, the external loads acting on the structure can be assessed. The basic idea behind iFEM is the optimization of a quadratic cost function of the difference between the measured and estimated values, with a high cost corresponding to a high precision of the measurements. In the present research it is firstly shown how the iFEM theory was broadened to accommodate for strain measurements through the construction of cost matrices to express the cost associated with the estimation of the response. The main focus of the research falls however on the influence that the measurement set-up has on the quality of the iFEM estimates. Only a limited number of measurements may be available, therefore it is essential to plan the measurement set-up carefully to obtain the highest quality of estimates. The number of measurements and the precision required to obtain a realistic result from an iFEM analysis is also a factor which plays a role and varies for different types of measurements. A numerical method for systematic sensitivity study of the measurements set-up without involving the actual measurement data, is presented. Two examples consisting of structures with both displacement measurements and strain measurements being taken, are presented. It illustrates how the sensitivity study method can be used to plan a more effective measurement set-up.
7
Sorensen, Thomas M. (Thomas Mead). "Aeroelastic analysis and sensitivity calculations using the Newton method." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/46446.
Повний текст джерела
8
Liang, Changnian. "A new surface resistance measurement method with ultrahigh sensitivity." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40299.
Повний текст джерелаАнотація:
A superconducting niobium triaxial cavity has been designed and fabricated to study residual surface resistance of planar superconducting materials. Unlike many other structures where the test samples are placed in strong magnetic field positions, the edge of a 25.4 mm or larger diameter sample in the triaxial cavity is located outside the strong field region. Therefore, the edge effects and possible losses between the thin film and the substrate have been minimized in this design, ensuring that the induced RF losses are intrinsic to the test material. The fundamental resonant frequency of the cavity is 1.5 GHz, the same as the working frequency of CEBAF cavities. The cavity has a compact size compared to its TE₀₁₁ counterpart, which makes it more sensitive to the sample's loss.Ph. D.
9
Bae, Sangjune. "Variable screening method using statistical sensitivity analysis in RBDO." Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/2817.
Повний текст джерелаАнотація:
A variable screening method is introduced to reduce the computational cost caused by the curse of dimension of high dimensional problem in RBDO. The screening method considers the output variance of the constraint functions and uses test-of-hypothesis to filter necessary variables. Also, the method is applicable to implicit functions as well as explicit functions. Suitable number of samples to obtain consistent test result is calculated. 3 examples are demonstrated with detailed variable screening procedure and RBDO result.
10
Corti, Fabrizio. "Viability of the overset method for geometrical sensitivity studies." Thesis, KTH, Flygdynamik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-223329.
Повний текст джерелаАнотація:
In the following thesis the overset method, also called chimera or overlapping meshes, is discussed and applied toa formula race car, in order to calculate its aerodynamic map. The proposed method would allow reducing set-uptime through automation and avoided re-meshing process. a A theoretical background is presented before thediscussion of the way this kind of approach has been set-up in Star-CCM+. Results are obtained and discussedfor various car positions. Further investigations are finally suggested to further assess the viability of the method.
11
Cross, David Michael. "Local Continuum Sensitivity Method for Shape Design Derivatives Using Spatial Gradient Reconstruction." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/48589.
Повний текст джерелаАнотація:
Novel aircraft configurations tend to be sized by physical phenomena that are largely neglected during conventional fixed wing aircraft design. High-fidelity fluid-structure interaction that accurately models geometric nonlinerity during a transient aeroelastic gust response is critical for sizing the aircraft configuration early in the design process. The primary motivation of this research is to develop a continuum shape sensitivity method that can support gradient-based design optimization of practical and multidisciplinary high-fidelity analyses. A local continuum sensitivity analysis (CSA) that utilizes spatial gradient reconstruction (SGR) and avoids mesh sensitivities is presented for shape design derivative calculations. Current design sensitivity analysis (DSA) methods have shortcomings regarding accuracy, efficiency, and ease of implementation. The local CSA method with SGR is a nonintrusive and element agnostic method that can be used with black box analysis tools, making it relatively easy to implement. Furthermore, it overcomes many of the accuracy issues documented in the current literature. The method is developed to compute design derivatives for a variety of applications, including linear and nonlinear static beam bending, linear and nonlinear transient gust analysis of a 2-D beam structure, linear and nonlinear static bending of rectangular plates, linear and nonlinear static bending of a beam-stiffened plate, and two-dimensional potential flow. The analyses are conducted using general purpose codes. For each example the design derivatives are validated with either analytic or finite difference solutions and practical numerical and modeling considerations are discussed. The local continuum shape sensitivity method with spatial gradient reconstruction is an accurate analytic design sensitivity method that is amenable to general purpose codes and black box tools.Ph. D.
12
Galuska, Chad M. "Limits of sensitivity to delayed timeout from avoidance." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1717.
Повний текст джерелаАнотація:
Thesis (M.A.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains vi, 34 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 100-102).
13
Ekmat, Benar, and Natalea Hermes. "Basic Creep of Young Concrete - Sensitivity in the Evaluation Method." Thesis, KTH, Betongbyggnad, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259760.
Повний текст джерелаАнотація:
Creep is defined as deformation that takes place under constant load after an initial elastic response. This thesis focuses on a material property problem area that concerns stress analysis. Focus is on stress development considering creep deformations occurring when a concrete structure is under load, i.e. stress analysis with viscoelastic properties of the material.From laboratory tests, both elastic modulus and deformations over time are estimated in an evaluation process. Usually, deformations of moist sealed samples are denoted basic creep. At Luleå Technical University creep measurements are evaluated according to the theory and methodology in Larson and Jonasson (2003a, 2003b). The model is denoted Linear Logarithmic Model, used for moist sealed concrete samples. This thesis involves an investigation of the evaluation procedure for basic creep performed in Thysell laboratory at LTU, to examine how sensitive the evaluation process is for the outcome from stress calculations. The calculations are performed in the Finite Element Method software ConTeSt Pro.The aim of the thesis is to analyze the sensitivity of evaluation of basic creep and of the Linear Logarithmic Model (LLM) by making changes in the evaluation process to see how different parameters sets effect calculated stresses/strains during through crack analysis. The changes are solely done in the relaxation spectra.The purpose is also to analyze how sensitive the changes made in the evaluation process are when typical cases are studied. The typical cases are defined with a structure of a newly cast wall on a mature slab, where various thickness of the wall during different temperature conditions are analyzed. The temperature conditions are named standard, winter and summer. With this, concrete is tested and evaluated to yield two material parameter sets useful for temperature - and stress calculations for young concrete.The material parameter sets were analyzed and their creep values were converted into relaxation values, i.e. relaxation spectra, according to Maxwell-chain formulation for LLM. ConTeSt calculations generate temperature development for the walls and slabs. Colour maps and values of the strain ratio for each studied case are also obtained.It can be established that the evaluation process of basic creep is sensitive. A conclusion to be drawn is that small changes in the relaxation spectra, gives changes in the results of stress calculations for the typical cases. As soon as we deviate from the temperature development for the test performed in the laboratory, either by changing the thickness of the wall or by testing different temperature conditions we get a different temperature development than the tested one. With the deviation in the calculated temperature development compared to the measured one, a difference in the calculated strain ratios for the two different material parameter sets created are found.The main discovery in this work is that when a geometry of the wall that is identical to the geometry of the concrete tested at the laboratory is analyzed, a small deviation in the calculations of strain is obtained. This is expected since the temperature development in the created wall will follow the temperature development of the tested concrete. When differing from this geometry and temperature case, differences in calculated strain ratios are observed.Krypning är deformation som sker under en konstant belastning och i detta examensarbete är det fokus på deformationer av fuktförseglade betongprover. Detta examensarbete är inriktat på olika materialparametersuppsättningar som berör spänningsanalyser. Det är fokus på spänningsutveckling med avseende på krypdeformationer som uppstår när en betongstruktur är under belastning. Detta gällande spänningsanalyser med viskoelastiska egenskaper hos betongmaterialet. Från laboratorietester bestäms både elasticitetsmodulen och deformationer över tid i en utvärderingsprocess. På Luleå tekniska universitet, utvärderas krypningsmätningarna enligt teorin och metodiken som finns beskriven i Larson och Jonasson (2003a, 2003b). Modellen är benämnd Linjär Logaritmisk Modell (LLM), som används för fuktförseglade betongprover. Examensarbetet innehåller en undersökning av utvärderingsprocessen för krypning utförda i Thysell laboratoriet vid LTU. Detta för att undersöka hur känslig utvärderingsprocessen är för resultatet av spänningsberäkningar. Beräkningarna utförs i Finita Elementprogrammet ConTeSt. Syftet med detta arbete är att analysera känsligheten i utvärderingen av krypning för fuktförseglade betongprover och för den Linjära Logaritmiska modellen genom att göra ändringar i utvärderingsprocessen för att se hur olika materialparametersuppsättningar påverkar beräknade spänningar under analys av genomgående sprickor. Ändringar görs endast i relaxationsspektra. Syftet är också att analysera hur känsliga förändringarna i utvärderingsprocessen är när olika typfall studeras. Typfallen definieras av ny gjuten vägg på en mogen betongplatta, där olika väggtjocklekar under olika temperaturförhållanden analyseras. Temperaturförhållandena benämns standard, vinter och sommar. Därvid testas och utvärderas betongen för att ge två materialparameteruppsättningar som är användbara för temperatur- och spänningsberäkningar för ung betong.Materialparameteruppsättningarna analyserades och deras krypvärden konverterades till relaxationsvärden, så kallade relaxations spektra, genom att använda Maxwell element för LLM. Från ConTeSt beräkningar erhålls värden för temperaturutveckling i vägg samt platta. Värmeutvecklingskarta tillsammans med värden på töjningskvoten för väggarna under varje studerat temperaturfall erhålls också från ConTeSt programmet. Det kan fastställas att den studerade utvärderingsprocessen för krypning är känslig. Små ändringar i relaxationsspektra ger variationer i resultatet av spänningsberäkningar för de olika typfallen. Så fort vi varierar den beräknade väggens temperaturutveckling från temperaturutvecklingen för testet som utförts i laboratoriet, antingen genom att ändra väggtjocklek eller genom att testa olika temperaturförhållanden, så erhålls en annorlunda temperaturutveckling än den som togs fram från laboratoriet. Med avvikelser i de beräknade temperaturutvecklingarna jämfört med den erhållna temperaturutvecklingen från den testade betongen i laboratoriet beräknas och analyseras skillnaden i töjningskvot. Den huvudsakliga upptäckten i detta arbete är att när den beräknade geometrin på väggen är identisk med den geometri som används för testriggen i laboratoriet, erhålls små variationer i de beräknade töjningskvoten. Detta är förväntat eftersom temperaturutvecklingen i den beräknade väggen är densamma som för betongen i testriggen i laboratoriet. När man avviker från den geometri eller de temperaturförhållandena som är identiska till dem i laboratoriet så erhålls större avvikelser i värden för den beräknade töjningskvoten.
14
Ruzvidzo, Martin. "Sensitivity analysis with simulated data errors : synthetic extinct generations method." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/5889.
Повний текст джерелаАнотація:
Includes abstract.Includes bibliographical references (leaves 59-61).
This study develops the key components of the Synthetic Extinct Generations (SEG+delta) method in trying to answer research questions raised by Dorrington and Timeaus (2008) and in the process investigates the different sets of combinations of the key components of the SEG+delta method when applied to the 23 error scenarios used by Hill and Choi (2004). In addition, the study determines the pattern of estimates of 4sfi15 per set of combinations, the combination that results in the best estimate of 45q15 per scenario and per combination of scenarios and the best combination that result in best estimate of 4sfi15 across all 23 error scenarios. The current study assesses the errors in age reported in censuses by comparing the weighted average of the ages of seven countries in the sub-Saharan African region to the age error pattern used by Hill and Choi (2004). These findings suggest that there is no significant difference (except of the zig-zag pattern in age errors at older ages in the Hill and Choi scenario) in general pattern of age errors of the sub-Saharan African region and the pattern used by Hill and Choi (2004).
15
Liu, Guangwu. "Pathwise sensitivity estimation for expectations of discontinuous functions /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?IELM%202009%20LIU.
Повний текст джерела
16
Zhao, Zhiye. "Shape design sensitivity analysis and optimization using the boundary element method." Thesis, University of South Wales, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254866.
Повний текст джерела
17
Barthelemy, Bruno. "Accuracy analysis of the semi-analytical method for shape sensitivity analysis." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/74754.
Повний текст джерелаАнотація:
The semi-analytical method, widely used for calculating derivatives of static response with respect to design variables for structures modeled by finite elements, is studied in this research. The research shows that the method can have serious accuracy problems for shape design variables in structures modeled by beam, plate, truss, frame, and solid elements. Local and global indices are developed to test the accuracy of the semi-analytical method. The local indices provide insight into the problem of large errors for the semi-analytical method. Local error magnification indices are developed for beam and plane truss structures, and several examples showing the severity of the problem are presented. The global index provides us with a general method for checking the accuracy of the semi-analytical method for any type of model. It characterizes the difference in errors between a general finite-difference method and the semi-analytical method. Moreover, a method improving the accuracy of the semi-analytical method (when possible) is provided. Examples are presented showing the use of the global index.Ph. D.
18
Turner, Aaron Michael. "Continuum Sensitivity Analysis for Shape Optimization in Incompressible Flow Problems." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78362.
Повний текст джерелаАнотація:
An important part of an aerodynamic design process is optimizing designs to maximize quantities such as lift and the lift-to-drag ratio, in a process known as shape optimization. It is the goal of this thesis to develop and apply understanding of mixed finite element method and sensitivity analysis in a way that sets the foundation for shape optimization. The open-source Incompressible Flow Iterative Solution Software (IFISS) mixed finite element method toolbox for MATLAB developed by Silvester, Elman, and Ramage is used. Meshes are produced for a backward-facing step problem, using built-in tools from IFISS as well as the mesh generation software Gmsh, and grid convergence studies are performed for both sets of meshes along a sampled data line to ensure that the simulations converge asymptotically with increasing mesh resolution. As a preliminary study of sensitivity analysis, analytic sensitivities of velocity components along the backward-facing step data line to inflow velocity parameters are determined and verified using finite difference and complex step sensitivity values. The method is then applied to pressure drag calculated by integrating the pressure over the surface of a circular cylinder in a freestream flow, and verified and validated using published simulation data and experimental data. The sensitivity analysis study is extended to shape optimization, wherein the shape of a circular cylinder is altered and the sensitivities of the pressure drag coefficient to the changes in the cylinder shape are determined and verified.Master of Science
19
Limache, Alejandro Cesar. "Aerodynamic Modeling Using Computational Fluid Dynamics and Sensitivity Equations." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/27033.
Повний текст джерелаАнотація:
A mathematical model for the determination of the aerodynamic forces acting on an aircraft is presented. The mathematical model is based on the generalization of the idea of aerodynamically steady motions. One important use of these results is the determination of steady (time-invariant) aerodynamic forces and moments. Such aerodynamic forces can be determined using computer simulation by determining numerically the associated steady flows around the aircraft when it is moving along such generalized steady trajectories. The method required the extension of standard (inertial) CFD formulations to general non-inertial reference frames. Generalized Navier-Stokes and Euler equations have been derived. The formulation is valid for all ranges of Mach numbers including transonic flow. The method was implemented numerically for the planar case using the generalized Euler equations. The developed computer codes can be used to obtain numerical flow solutions for airfoils moving in general steady motions (i.e. circular motions). From these numerical solutions it is possible to determine the variation of the lift, drag and pitching moment with respect to the pitch rate at different Mach numbers and angles of attack. One of the advantages of the mathematical model developed here is that the aerodynamic forces become well-defined functions of the motion variables (including angular rates). In particular, the stability derivatives are associated with partial derivatives of these functions. These stability derivatives can be computed using finite differences or the sensitivity equation method.Ph. D.
20
Kim, Hyunsoon. "Coupled Adjoint-based Sensitivity Analysis using a FSI Method in Time Spectral Form." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/94132.
Повний текст джерелаАнотація:
A time spectral and coupled adjoint based sensitivity analysis of rotor blade is carried out in this study. The time spectral method is an efficient technique to solve unsteady periodic problems by transforming unsteady equation of motion to a steady state one. Due to the availability of the governing equations in the steady form, the steady form of the adjoint equations can be applied for the sensitivity analysis of the coupled fluid-structure system. An expensive computational time and memory requirement for the unsteady adjoint sensitivity analysis is thus avoided. A coupled analysis of fluid, structural, and flight dynamics is carried out through a CFD/CSD/CA coupling procedure that combines FSI analysis with enforced trim condition. Coupled sensitivity analysis results and their validations are presented and compared with aerodynamics only sensitivity analysis results. The fluid-structure coupled adjoint based sensitivity analysis will be applied to the shape optimization of a rotor blade in the future work. Minimization of required power is the objective of the optimization problem with constraints on thrust and drag of the rotor. The bump functions are considered as the design variables. Rotor blade shape changes are obtained by using the bump function on the surface of the airfoil sections along the span.Doctor of Philosophy
The work in this dissertation is motivated by the reducing the computational cost at the early design stage with guaranteed accuracy. In the research, the author proposes that the goal can be achieve through coupled adjoint based sensitivity analysis using a fluid structure interaction in time spectral form. Adjoint based sensitivity analysis is very efficient for solving design problems with a large number of design variables. The time spectral approach is used to overcome inefficient calculation of rotor flows by expressing flow and structural state variables as Fourier series with small number of harmonics. The accuracy and the efficiency of flow solver are examined by simulating UH-60A forward flight condition. A significant reduction in the computational cost is achieved by its Fourier series form of the periodic time response and the assumption of periodic steady state. A good agreement between time accurate and time spectral analysis is noted for the high speed forward flight condition of UH-60A configuration. Prediction from both methods also agree quite well with the experimental data. The adjoint based sensitivity analysis results are compared with the finite difference sensitivity analysis results. Even with presence of small discrepancies, these two results show a good agreement to each other. Coupled sensitivity analysis includes not only the effect of fluid state changes but also the contribution of structural deformation.
21
Lewis, Doris Trinh 1957. "A ROBUST METHOD FOR USING MAINTAINABILITY COST MODELS (RELIABILITY, OPTIMIZATION, SENSITIVITY, UNCERTAINTY)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/292098.
Повний текст джерела
22
Han, Bongtae. "Extension of Moire interferometry into the ultra-high sensitivity domain." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/37748.
Повний текст джерелаАнотація:
The objective of this research was to provide means for the experimental analysis of deformations encountered in micromechanics. Whole field contour maps of U and V displacements in a microscopic field of view were desired. Since displacements within a small field can be very small even when strains are large, ultra-high sensitivity is required. The specific objective was displacement sensitivity of 50 nm per fringe contour, which corresponds to that of moire with 20,000 lines per mm, in combination with spatial resolution of the optical microscope (2-5 μm).
The objective was achieved by the following developments. First, the basic sensitivity of moire interferometry was increased beyond the previously conceived theoretical limit. This was accomplished by creating the virtual reference grating inside a refractive medium instead of air, thus shortening the wavelength of light. A very compact four beam moire interferometer in a refractive medium was developed for microscopic viewing, which produced a basic sensitivity of 208 nm per fringe order. Its configuration made it inherently stable and relatively insensitive to environmental disturbances. An optical microscope was employed as the image recording system to obtain the desired spatial resolution.
Secondly, a fringe multiplication scheme was implemented. Here, an automatic fringe shifting and fringe sharpening scheme was developed, wherein very thin fringe contours of order N* = βN were produced, where N is the fringe order in the basic moire pattern and β is a fringe multiplication factor. A factor of 12 was achieved, providing a sensitivity of 17 nm per fringe contour. This corresponds to moire with 57,600 lines per mm (1,463,000 lines per in.), which exceeds the sensitivity objective. The mechanical and electronic systems implemented here are remarkably robust and quick.
The method was demonstrated with three practical applications: interface strains in a thick 0°/90° graphite/epoxy composite, fiber/matrix deformations of metal/matrix composites, and thermal deformation around a solder joint in a microelectronic subassembly.Ph. D.
23
Figiel, Lukasz. "Sensitivity Analysis of Interface Fatigue Crack Propagation in Elastic Composite Laminates." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1102358246078-89903.
Повний текст джерелаАнотація:
Composite laminates are an important subject of modern technology and engineering. The most common mode of failure in these materials is probably interlaminar fracture (delamination). Delamination growth under applied fatigue loads usually leads to structural integrity loss of the composite laminate, and hence its catastrophic failure. It is known that several parameters can affect the fatigue fracture performance of laminates. These include the constituent material properties, composite geometry, fatigue load variables or environmental factors. The knowledge about effects of these parameters on fatigue delamination growth can lead to a better understanding of composite fatigue fracture behaviour. Effects of some of these parameters can be elucidated by undertaking appropriate sensitivity analysis combined with the finite element method (FEM) and related software. The purpose of this work was three-fold. The first goal was the elaboration and computational implementation of FEM-based numerical strategies for the sensitivity analysis of interface fatigue crack propagation in elastic composite laminates. The second goal of this work was the numerical determination and investigation of displacement and stress fields near the crack tip, contact pressures along crack surfaces, mixed mode angle, energy release rate and the number of cumulative fatigue cycles. The third aim of the present study was to use the developed strategies to evaluate numerically the sensitivity gradients of the total energy release rate and fatigue life with respect to design variables of the curved boron/epoxy-aluminium (B/Ep-Al) composite laminate in two different material configurations under cyclic shear of constant amplitude. This study provided novel strategies for undertaking sensitivity analysis of the delamination growth under fatigue loads for elastic composite laminates using the package ANSYS. The numerical results of the work shed more light on mechanisms of interfacial crack propagation under cyclic shear in the case of a curved B/Ep-Al composite laminate. Moreover, the outcome of the sensitivity gradients demonstrated some advantages for using the sensitivity analysis to pinpoint directions for the optimisation of fatigue fracture performance of elastic laminates. The strategies proposed in this work can be used to study the sensitivity of the interface fatigue crack propagation in other elastic laminates, if the crack propagates at the interface between the elastic and isotropic components. However, the strategies can be potentially extended to composites with interfacial cracks propagating between two non-isotropic constituents under a constant amplitude fatigue load. Finally, the strategies can also be used to undertake the sensitivity analysis of composite fatigue life with respect to variables of fatigue load.
24
Masinde, Brian. "Birds' Flight Range. : Sensitivity Analysis." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166248.
Повний текст джерелаАнотація:
’Flight’ is a program that uses flight mechanics to estimate the flight range of birds. This program, used by ornithologists, is only available for Windows OS. It requires manual imputation of body measurements and constants (one observation at a time) and this is time-consuming. Therefore, the first task is to implement the methods in R, a programming language that runs on various platforms. The resulting package named flying, has three advantages; first, it can estimate flight range of multiple bird observations, second, it makes it easier to experiment with different settings (e.g. constants) in comparison to Flight and third, it is open-source making contribution relatively easy. Uncertainty and global sen- sitivity analyses are carried out on body measurements separately and with various con- stants. In doing so, the most influential body variables and constants are discovered. This task would have been near impossible to undertake using ’Flight’. A comparison is made amongst the results from a crude partitioning method, generalized additive model, gradi- ent boosting machines and quasi-Monte Carlo method. All of these are based on Sobol’s method for variance decomposition. The results show that fat mass drives the simulations with other inputs playing a secondary role (for example mechanical conversion efficiency and body drag coefficient).
25
鄧國良 and Kwok-leong Tang. "Sensitivity analysis of bootstrap methods." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31977479.
Повний текст джерела
26
Tang, Kwok-leong. "Sensitivity analysis of bootstrap methods." [Hong Kong] : University of Hong Kong, 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13793792.
Повний текст джерела
27
Brandt, Katrin [Verfasser]. "Sensitivity-based method to support early stage design of biochemical processes / Katrin Brandt." München : Verlag Dr. Hut, 2017. http://d-nb.info/1137024208/34.
Повний текст джерела
28
Volland, Nelly A. "Sensitivity improvement of a nuclear magnetic resonance method to monitor a bioartificial pancreas." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024800.
Повний текст джерела
29
Di, Gangi Pietro. "Study of the sensitivity of the XENON1T experiment with the profile likelihood method." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8348/.
Повний текст джерелаАнотація:
Oggi sappiamo che la materia ordinaria rappresenta solo una piccola parte dell'intero contenuto in massa dell'Universo. L'ipotesi dell'esistenza della Materia Oscura, un nuovo tipo di materia che interagisce solo gravitazionalmente e, forse, tramite la forza debole, è stata avvalorata da numerose evidenze su scala sia galattica che cosmologica. Gli sforzi rivolti alla ricerca delle cosiddette WIMPs (Weakly Interacting Massive Particles), il generico nome dato alle particelle di Materia Oscura, si sono moltiplicati nel corso degli ultimi anni.
L'esperimento XENON1T, attualmente in costruzione presso i Laboratori Nazionali del Gran Sasso (LNGS) e che sarà in presa dati entro la fine del 2015, segnerà un significativo passo in avanti nella ricerca diretta di Materia Oscura, che si basa sulla rivelazione di collisioni elastiche su nuclei bersaglio. XENON1T rappresenta la fase attuale del progetto XENON, che ha già realizzato gli esperimenti XENON10 (2005) e XENON100 (2008 e tuttora in funzione) e che prevede anche un ulteriore sviluppo, chiamato XENONnT.
Il rivelatore XENON1T sfrutta circa 3 tonnellate di xeno liquido (LXe) e si basa su una Time Projection Chamber (TPC) a doppia fase. Dettagliate simulazioni Monte Carlo della geometria del rivelatore, assieme a specifiche misure della radioattività dei materiali e stime della purezza dello xeno utilizzato, hanno permesso di predire con accuratezza il fondo atteso.
In questo lavoro di tesi, presentiamo lo studio della sensibilità attesa per XENON1T effettuato tramite il metodo statistico chiamato Profile Likelihood (PL) Ratio, il quale nell'ambito di un approccio frequentista permette un'appropriata trattazione delle incertezze sistematiche.
In un primo momento è stata stimata la sensibilità usando il metodo semplificato Likelihood Ratio che non tiene conto di alcuna sistematica. In questo modo si è potuto valutare l'impatto della principale incertezza sistematica per XENON1T, ovvero quella sulla emissione di luce di scintillazione dello xeno per rinculi nucleari di bassa energia.
I risultati conclusivi ottenuti con il metodo PL indicano che XENON1T sarà in grado di migliorare significativamente gli attuali limiti di esclusione di WIMPs; la massima sensibilità raggiunge una sezione d'urto σ=1.2∙10-47 cm2 per una massa di WIMP di 50 GeV/c2 e per una esposizione nominale di 2 tonnellate∙anno. I risultati ottenuti sono in linea con l'ambizioso obiettivo di XENON1T di abbassare gli attuali limiti sulla sezione d'urto, σ, delle WIMPs di due ordini di grandezza. Con tali prestazioni, e considerando 1 tonnellata di LXe come massa fiduciale, XENON1T sarà in grado di superare gli attuali limiti (esperimento LUX, 2013) dopo soli 5 giorni di acquisizione dati.
30
Lee, Abraham. "A Hybrid Method for Sensitivity Optimization With Application to Radio-Frequency Product Design." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4358.
Повний текст джерелаАнотація:
A method for performing robust optimal design that combines the efficiency of experimental designs and the accuracy of nonlinear programming (NLP) has been developed, called Search-and-Zoom. Two case studies from the RF and communications industry, a high-frequency micro-strip band-pass filter (BPF) and a rectangular, directional patch antenna, were used to show that sensitivity optimization could be effectively performed in this industry and to compare the computational efficiency of traditional NLP methods (using fmincon solver in MATLAB R2013a) and they hybrid method Search-and-Zoom. The sensitivity of the BPF's S11 response was reduced from 0.06666 at the (non-robust) nominal optimum to 0.01862 at the sensitivity optimum. Feasibility in the design was improved by reducing the likelihood of violating constraints from 20% to nearly 0%, assuming RSS (i.e., normally-distributed) input tolerances and from 40% to nearly 0%, assuming WC (i.e., uniformly-distributed) input tolerances. The sensitivity of the patch antenna's S11 function was also improved from 0.02068 at the nominal optimum to 0.0116 at the sensitivity optimum. Feasibility at the sensitivity optimum was estimated to be 100%, and thus did not need to be improved. In both cases, the computation effort to reach the sensitivity optima, as well as the sensitivity optima with RSS and WC feasibility robustness, was reduced by more than 80% (average) by using Search-and-Zoom, compared to the NLP solver.
31
Rovira, Ricardo E. Basora. "Vehicle classification method for use with rapidly emplaced mobile bridges| A sensitivity study." Thesis, Purdue University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10044106.
Повний текст джерелаАнотація:
A feature detection algorithm is developed to determine which type of vehicle crosses a mobile bridge using acceleration responses. The purpose of this thesis is to examine the results sensitivity of the algorithm to various parameters that influence the ability to correctly classify vehicles. Each of these results will play a role in developing the most suitable procedure.
Using numerical and experimental results, the parameters studied are: bridge length, vehicle speed, noise, sensor filtering, and soil conditions. Each parameter is varied individually to determine how much it affects the ability of the method to classify vehicles traversing the bridge. Consideration is given to how parameters could be controlled under real world conditions to yield reliable results. The investigations demonstrate that results vary slightly to noise levels, the length of the bridge is constant once emplaced, sensor filtering setting can be fixed, soil condition impacts are minimum, and the vehicle speed can be controlled if a ground guide is used.
Based on the observations, a generalized procedure is prepared which consists of: creating a database with multiples parameters, controlling the parameters within realistic constraints, and grouping similar vehicle responses. The procedure aims to provide the best environment to produce reliable detection rates.
32
Maguire, David R. "Sensitivity of preference to reinforcement amount depends upon the method used to manipulate amount /." Electronic version (PDF), 2006. http://dl.uncw.edu/etd/2007-1/maguired/davidmaguire.pdf.
Повний текст джерела
33
Kovalova, А. А., O. G. Avrunin, and О. Г. Аврунін. "Research of the sensitivity of the computer capillaroscopy method under local changes in temperature." Thesis, Кременчук, Україна, 2020. http://openarchive.nure.ua/handle/document/13786.
Повний текст джерелаАнотація:
The possibilities of the method of computerized capillaroscopy for studying the structure of the capillaries of the skin of the hands after exposure to temperature are considered. With local frostbite, there is a lack of sensitivity and insufficient expression of blood vessels, their blanching caused by constriction. The capillaroscopic picture is relatively normal, however, some characteristic changes can be observed: the blood flow slows down, external thinning of the vessel walls is observed, the capillaries are somewhat deformed, some of them empty.
34
Olesko, Brian M. "Dynamic contrast sensitivity : methods and measurements /." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09052009-040416/.
Повний текст джерела
35
Alexe, Mihai. "Adjoint-based space-time adaptive solution algorithms for sensitivity analysis and inverse problems." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/37515.
Повний текст джерелаАнотація:
Adaptivity in both space and time has become the norm for solving problems modeled by partial differential equations. The size of the discretized problem makes uniformly refined grids computationally prohibitive. Adaptive refinement of meshes and time steps allows to capture the phenomena of interest while keeping the cost of a simulation tractable on the current hardware. Many fields in science and engineering require the
solution of inverse problems where parameters for a given model are estimated based on available measurement information. In contrast to forward (regular) simulations, inverse problems have not extensively benefited from the adaptive solver technology. Previous research in inverse problems has focused mainly on the continuous approach to calculate sensitivities, and has typically employed fixed time and space meshes in the solution process. Inverse problem solvers that make exclusive use of uniform or static meshes avoid complications such as the differentiation of mesh motion equations, or inconsistencies in the sensitivity equations between subdomains with different refinement levels. However, this comes at the cost of low computational efficiency. More efficient computations are possible through judicious use of adaptive mesh refinement, adaptive time steps, and the discrete adjoint method. This dissertation develops a complete framework for fully discrete adjoint sensitivity analysis and inverse problem solutions, in the context of time dependent, adaptive mesh, and adaptive step models. The discrete framework addresses all the necessary ingredients
of a stateâ ofâ theâ art adaptive inverse solution algorithm: adaptive mesh and time step refinement, solution grid transfer operators, a priori and a posteriori error analysis and estimation, and discrete adjoints for sensitivity analysis of fluxâ limited numerical algorithms.Ph. D.
36
Ezertas, Ahmet Alper. "Sensitivity Analysis Using Finite Difference And Analytical Jacobians." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611067/index.pdf.
Повний текст джерелаАнотація:
The Flux Jacobian matrices, the elements of which are the derivatives of the flux vectors with respect to the flow variables, are needed to be evaluated in implicit flow solutions and in analytical sensitivity analyzing methods. The main motivation behind this thesis study is to explore the accuracy of the numerically evaluated flux Jacobian matrices and the effects of the errors in those matrices on the convergence of the flow solver, on the accuracy of the sensitivities and on the performance of the design optimization cycle. To perform these objectives a flow solver, which uses exact Newton&rsquos method with direct sparse matrix solution technique, is developed for the Euler flow equations. Flux Jacobian is evaluated both numerically and analytically for different upwind flux discretization schemes with second order MUSCL face interpolation. Numerical flux Jacobian matrices that are derived with wide range of finite difference perturbation magnitudes were compared with analytically derived ones and the optimum perturbation magnitude, which minimizes the error in the numerical evaluation, is searched. The factors that impede the accuracy are analyzed and a simple formulation for optimum perturbation magnitude is derived. The sensitivity derivatives are evaluated by direct-differentiation method with discrete approach. The reuse of the LU factors of the flux Jacobian that are evaluated in the flow solution enabled efficient sensitivity analysis. The sensitivities calculated by the analytical Jacobian are compared with the ones that are calculated by numerically evaluated Jacobian matrices. Both internal and external flow problems with varying flow speeds, varying grid types and sizes are solved with different discretization schemes. In these problems, when the optimum perturbation magnitude is used for numerical Jacobian evaluation, the errors in Jacobian matrix and the sensitivities are minimized. Finally, the effect of the accuracy of the sensitivities on the design optimization cycle is analyzed for an inverse airfoil design performed with least squares minimization.
37
Philander, Oscar. "Mathematical modelling of welding : sensitivity of residual stresses and thermal dilatations on welding parameters." Thesis, Peninsula Technikon, 1998. http://hdl.handle.net/20.500.11838/2227.
Повний текст джерелаАнотація:
Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, 1998.In South Africa, the determination of residual stress distribution and undesirable metallurgical phase fractions that are formed in components during welding are been dealt with in a destructive or semi-destructive manner. This dissertation is an attempt at enhancing the acquisition of residual components found in welded structures. It shows how finite element methods can be used to obtain these results. TIG welding is modeled as a thermo-mechano-metallurgical (TMM) problem. The mathematical and finite element models for welding described in this study is based on the work performed by Ronda and Oliver. These models has not yet fully been incorporated into any of the existing computational tools and therefor, a commercial computational software program, SYSWELD 2, was employed to perform the welding simulations. The Leblond material models are incorporated into this software program, and the model that is used for this study is described in this text. Computational simulations were performed to study the effects that the sensitivity of welding parameters would have on the resulting shape and size of Heat Affected Zones, depth and width of penetration, temperature fields, metallurgical solid phase fractions, as well as residual stress distribution and deformation. The results of these simulations were compared to laboratory experiments.
38
Napelenok, Sergey L. "Sensitivity Analysis in Air Quality Models for Particulate Matter." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14083.
Повний текст джерелаАнотація:
Fine particulate matter (PM2.5) has been associated with a variety of problems that include adverse health effects, reduction in visibility, damage to buildings and crops, and possible interactions with climate. Although stringent air quality regulations are in place, policy makers need efficient tools to test a wide range of control strategies. Sensitivity analysis provides predictions on how the interdependent concentrations of various PM2.5 components and also gaseous pollutant species will respond to specific combinations of precursor emission reductions. The Community Multiscale Air Quality Model (CMAQ) was outfitted with the Decoupled Direct Method in 3D for calculating sensitivities of particulate matter (DDM-3D/PM). This method was evaluated and applied to high PM2.5 episodes in the Southeast United States. Sensitivities of directly emitted particles as well as those formed in the atmosphere through chemical and physical processing of emissions of gaseous precursors such as SO2, NOx, VOCs, and NH3 were calculated. DDM-3D/PM was further extended to calculate receptor oriented sensitivities or the Area of Influence (AOI). AOI analysis determines the geographical extent of relative air pollutant precursor contributions to pollutant levels at a specific receptor of interest. This method was applied to Atlanta and other major cities in Georgia. The tools developed here (DDM-3D/PM and AOI) provide valuable information to those charged with air quality management.
39
Gruber, Matthew. "A new sensitivity analysis and solution method for scintillometer measurements of area-average turbulent fluxes." Thesis, University of Alaska Fairbanks, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1547616.
Повний текст джерелаАнотація:
Scintillometer measurements of the turbulence inner-scale length lo and refractive index structure function C2n allow for the retrieval of large-scale area-averaged turbulent fluxes in the atmospheric surface layer. This retrieval involves the solution of the non-linear set of equations defined by the Monin-Obukhov similarity hypothesis. A new method that uses an analytic solution to the set of equations is presented, which leads to a stable and efficient numerical method of computation that has the potential of eliminating computational error. Mathematical expressions are derived that map out the sensitivity of the turbulent flux measurements to uncertainties in source measurements such as lo. These sensitivity functions differ from results in the previous literature; the reasons for the differences are explored.
40
Ikola, Suvi. "Dentin hypersensitivity and its treatment methods." Turku : Turun Yliopisto, 2001. http://books.google.com/books?id=WiBqAAAAMAAJ.
Повний текст джерела
41
竹内, 謙善, Kenzen TAKEUCHI, 竜. 笹岡, Ryu SASAOKA, 秀幸 畔上, Hideyuki AZEGAMI, 紀明 川上 та Noriaki Kawakami. "脊柱特発性側彎症の治療法に関する検討 （座屈説に基く感度解析）". 日本機械学会, 2000. http://hdl.handle.net/2237/12190.
Повний текст джерела
42
Timsina, Tirtha Prasad. "Sensitivities in Option Pricing Models." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/28904.
Повний текст джерелаАнотація:
The inverse problem in finance consists of determining the unknown parameters of
the pricing equation from the values quoted from the market. We formulate the
inverse problem as a minimization problem for an appropriate cost function to minimize
the difference between the solution of the model and the market observations.
Efficient gradient based optimization requires accurate gradient estimation of the
cost function. In this thesis we highlight the adjoint method for computing gradients
of the cost function in the context of gradient based optimization and show its
importance. We derive the continuous adjoint equations with appropriate boundary
conditions for three main option pricing models: the Black-Scholes model, the Hestonâ s
model and the jump diffusion model, for European type options. These adjoint
equations can be used to compute the gradient of the cost function accurately for
parameter estimation problems.
The adjoint method allows efficient evaluation of the gradient of a cost function F(¾)
with respect to parameters ¾ where F depends on ¾ indirectly, via an intermediate
variable. Compared to the finite difference method and the sensitivity equation
method, the adjoint equation method is very efficient in computing the gradient
of the cost function. The sensitivity equations method requires solving a PDE
corresponding to each parameter in the model to estimate the gradient of the cost
function. The adjoint method requires solving a single adjoint equation once. Hence,
for a large number of parameters in the model, the adjoint equation method is very
efficient.
Due to its nature, the adjoint equation has to be solved backward in time. The
adjoint equation derived from the jump diffusion model is harder to solve due to its
non local integral term. But algorithms that can be used to solve the Partial Integro-
Differential Equation (PIDE) derived from jump diffusion model can be modified to
solve the adjoint equation derived from the PIDE.Ph. D.
43
Lewis, Elizabeth. "A mixed method investigation of the Rubber Hand Illusion." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/a-mixed-method-investigation-of-the-rubber-hand-illusion(e2d6456f-c093-4061-bd16-12e854915639).html.
Повний текст джерелаАнотація:
Embodiment is the experience of one's own body. It is often studied using the Rubber Hand Illusion (RHI). This illusion varies the consistency between visual, tactile and proprioceptive signals to elicit a change to embodiment. Changes to embodiment are typically measured using a single sensory outcome measure of proprioceptive drift, which is interpreted as a proxy measure of embodiment. This approach obscures the unique contribution of other modalities such as vision and touch. The work presented in this thesis uses a mixed method approach to investigate the unique contribution of visual, tactile and proprioceptive modalities within the multisensory process of embodiment. In study one, a qualitative analysis showed that when visual-tactile discrepancies were present in the RHI, participants described both body ownership and body extension type changes to embodiment, and changes to tactile perception. In study two, psychophysical measurements of the RHI showed changes to visual, tactile and proprioceptive aspects of embodiment, suggesting that embodiment in the RHI could be measured using multiple sensory outcomes. Studies three and four assessed the utility of measuring multiple sensory outcomes of the RHI, by exploring changes to embodiment following internal and external forms of body perception training. Study three showed that brief body scan meditation, as a form of internal body perception training, reduced the longevity of the visual sensory outcome of the RHI and that this reduction was negatively correlated with improvements in interoceptive sensitivity. Study four showed that learning about the body through anatomical dissection training, as a form of external body perception training, reduced the longevity of the visual sensory outcome measure and decreased interoceptive sensitivity, but only in medical students who were high in trait personal distress. Collectively, these findings suggest that aspects of the multisensory processes of embodiment can become specialised and identify some unique contributions of individual sensory modalities to embodiment. The proprioceptive sensory outcome appears to be stable over time but the visual sensory outcome is a longer-term change to embodiment, which is susceptible to interference from body perception training. In study five, confirmatory factor analysis was used to assess the psychometric properties of an embodiment change questionnaire measuring body ownership, body extension and perceived causality in the RHI. Factor scores from the questionnaire were correlated with visual and proprioceptive outcome measures of the RHI and measures of trait empathy. The results suggested factor scores had better convergent validity than the standard illusion score used in previous research. This work has improved subjective and perceptual measures of the RHI and specified ways that individual sensory modalities provide a unique contribution to embodiment. The methods developed have further applications for studying the multisensory process of embodiment and investigating embodiment in a number of clinical groups.
44
Zhang, Wenxian. "Direct sensitivity techniques in regional air quality models: development and application." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52941.
Повний текст джерелаАнотація:
Sensitivity analysis based on a chemical transport model (CTM) serves as an important approach towards better understanding the relationship between trace contaminant levels in the atmosphere and emissions, chemical and physical processes. Previous studies on ozone control identified the high-order Decoupled Direct Method (HDDM) as an efficient tool to conduct sensitivity analysis. Given the growing recognition of the adverse health effects of fine particulate matter (i.e., particles with an aerodynamic diameter less than 2.5 micrometers (PM2.5)), this dissertation presents the development of a HDDM sensitivity technique for particulate matter and its implementation it in a widely used CTM, CMAQ. Compared to previous studies, two new features of the implementation are 1) including sensitivities of aerosol water content and activity coefficients, and 2) tracking the chemical regimes of the embedded thermodynamic model. The new features provide more accurate sensitivities especially for nitrate and ammonium. Results compare well with brute force sensitivities and are shown to be more stable and computationally efficient. Next, this dissertation explores the applications of HDDM. Source apportionment analysis for the Houston region in September 2006 indicates that nonlinear responses accounted for 3.5% to 33.7% of daily average PM2.5, and that PM2.5 formed rapidly during night especially in the presence of abundant ozone and under stagnant conditions. Uncertainty analysis based on the HDDM found that on average, uncertainties in the emissions rates led to 36% uncertainty in simulated daily average PM2.5 and could explain much, but not all, of the difference between simulated and observed PM2.5 concentrations at two observations sites. HDDM is then applied to assess the impact of flare VOC emissions with temporally variable combustion efficiency. Detailed study of flare emissions using the 2006 Texas special inventory indicates that daily maximum 8-hour ozone at a monitoring site can increase by 2.9 ppb when combustion is significantly decreased. The last application in this dissertation integrates the reduced form model into an electricity generation planning model, and enables representation of geospatial dependence of air quality-related health costs in the optimization process to seek the least cost planning for power generation. The integrated model can provide useful advice on selecting fuel types and locations for power plants.
45
Bettemir, Onder Halis. "Sensitivity And Error Analysis Of A Differential Rectification Method For Ccd Frame Cameras And Pushbroom Scanners." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607708/index.pdf.
Повний текст джерелаАнотація:
In this thesis, sensitivity and error analysis of a differential rectification method were performed by using digital images taken by a frame camera onboard BILSAT and pushbroom scanner on ASTER. Three methods were implemented for Sensitivity and Uncertainty analysis: Monte Carlo, covariance analysis and FAST (Fourier Amplitude Sensitivity Test). A parameter estimation procedure was carried out on the basis of so called Mixed Model extended by some suitable additional regularization parameters to stabilize the solution for improper geometrical conditions of the imaging system. The effectiveness and accuracy of the differential rectification method were compared with other rectification methods and the results were analyzed. Furthermore the differential method is adapted to the pushbroom scanners and software which provides rectified images from raw satellite images was developed.
46
Craig, Martha. "Land use and Wetland Function: A Sensitivity Analysis of the VIMS Nontidal Wetland Functional Assessment Method." W&M ScholarWorks, 1992. https://scholarworks.wm.edu/etd/1539617640.
Повний текст джерела
47
Xu, Hailan. "Buckling, Postbuckling and Imperfection Sensitivity Analysis of Different Type of Cylindrical Shells by Hui's Postbuckling Method." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1781.
Повний текст джерелаАнотація:
Hui and Chen (1986) were the first to show that the well-known Koiter’s General Theory of Elastic Stability of 1945 can be significantly improved by evaluating the postbuckling b coefficient at the actual applied load, rather than at the classical buckling load. Such improvement method was demonstrated to be (1) very simple to apply with no tedious algebra, (2) significant reduction in imperfection sensitivity and (3) although it is still asymptotically valid, there exists a significant extension of the range of validity involving larger imperfection amplitudes. Strictly speaking, Koiter’s theory of 1945 is valid only for vanishingly small imperfection amplitudes. Hence such improved method is termed Hui’s Postbuckling method. This study deals with the postbuckling and imperfection sensitivity of different kinds of cylinders, using the Hui’s postbuckling method. For unstiffened cylinder and laminate cylinder the results are compared with ABAQUS simulation results, and a parameter variation of stringer/ring stiffened cylinder is also evaluated. A significant positive shift of the postbuckling b coefficient is found which indicates that Koiter's general stability theory of 1945 has significantly overestimated the imperfection sensitivity of the structure. Also, compared with the Koiter's general stability theory, the valid region is significantly increased by using Hui's postbuckling method.
48
Takeuchi, Kenzen, Hideyuki Azegami, Shunji Murachi, Junzoh Kitoh, Yoshito Ishida, Noriaki Kawakami, and Mitsunori Makino. "Study on Treatment with Respect to Idiopathic Scoliosis (Sensitivity Analysis Based on Buckling Theory)." 日本機械学会, 2001. http://hdl.handle.net/2237/7282.
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Aweya, James. "Sensitivity methods for congestion control in computer networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0021/NQ48085.pdf.
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Dreißigacker, Christoph [Verfasser]. "Searches for continuous gravitational waves : sensitivity estimation and deep learning as a novel search method / Christoph Dreißigacker." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/1220422142/34.
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