Relevant bibliographies by topics / Force models / Dissertations / Theses

Dissertations / Theses on the topic 'Force models'

To see the other types of publications on this topic, follow the link: Force models.
Author: Grafiati
Published: 10 December 2022
Last updated: 29 January 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'Force models.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

Razavi, Seyed Mostafa. "CROSS-PLATFORM FORCE FIELD DEVELOPMENT BASED ON FORCE-SMOOTHED POTENTIAL MODELS." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1590770530909963.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Harris, Sinclair M. "Comparison of three Combat Logistic Force models." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from the National Technical Information Service, 1989. http://edocs.nps.edu/npspubs/scholarly/theses/1989/Mar/89Mar_Harris.pdf.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Closson, Taunia Lydia Lynn, and University of Lethbridge Faculty of Arts and Science. "Biological models with a square wave driving force." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2002, 2002. http://hdl.handle.net/10133/146.

Full text
Abstract:
Systems that require a driving force of some kind are very common in physical and biological settings. Driving forces in a biological context are usually referred to as rhythms, pulses or clocks. Here we are interested in the effect of adding a square wave periodic driving force to a biological model. This is intended to model inputs from biological circuits with all-or-none or switch-like resposes. We study a model of cell division proposed by Novak and Tyson. Our switched input is intended to model the interaction of the mitotic oscillator with an ultradian clock. We thoroughly characterize the behaviour as a function of the durations of the active and inactive phases. We also study a model of vein formation in plant leaves proposed by Mitchison. Pulsed hormonal release greatly accelerates vein formation in this model.
x, 105 leaves : ill. (some col.) ; 29 cm.
APA, Harvard, Vancouver, ISO, and other styles
4

Wu, Ming-Cheng. "Estimating operating and support models for U.S. Air Force Aircraft." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA376488.

Full text
Abstract:
Thesis (M.S. in Management) Naval Postgraduate School, March 2000.
Thesis advisor(s): Hildebrandt, Gregory G. ; Liao, Shu S. "March 2000." Includes bibliographical references (p. 57-59). Also available in print.
APA, Harvard, Vancouver, ISO, and other styles
5

Wróblewska, Liliana. "Refinement of reduced protein models with all-atom force fields." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/26606.

Full text
Abstract:
The goal of the following thesis research was to develop a systematic approach for the refinement of low-resolution protein models, as a part of the protein structure prediction procedure. Significant progress has been made in the field of protein structure prediction and the contemporary methods are able to assemble correct topology for a large fraction of protein domains. But such approximate models are often not detailed enough for some important applications, including studies of reaction mechanisms, functional annotation, drug design or virtual ligand screening. The development of a method that could bring those structures closer to the native is then of great importance. The minimal requirements for a potential that can refine protein structures is the existence of a correlation between the energy with native similarity and the scoring of the native structure as being lowest in energy. Extensive tests of the contemporary all-atom physics-based force fields were conducted to assess their applicability for refinement. The tests revealed flatness of such potentials and enabled the identification of the key problems in the current approaches. Guided by these results, the optimization of the AMBER (ff03) force field was performed that aimed at creating a funnel shape of the potential, with the native structure at the global minimum. Such shape should facilitate the conformational search during refinement and drive it towards the native conformation. Adjusting the relative weights of particular energy components, and adding an explicit hydrogen bond potential significantly improved the average correlation coefficient of the energy with native similarity (from 0.25 for the original ff03 potential to 0.65 for the optimized force field). The fraction of proteins for which the native structure had lowest energy increased from 0.22 to 0.90. The new, optimized potential was subsequently used to refine protein models of various native-similarity. The test employed 47 proteins and 100 decoy structures per protein. When the lowest energy structure from each trajectory was compared with the starting decoy, we observed structural improvement for 70% of the models on average. Such an unprecedented result of a systematic refinement is extremely promising in the context of high-resolution structure prediction.
APA, Harvard, Vancouver, ISO, and other styles
6

Hazra, Siddharth. "An investigation of nonlinear tip-sample force models for nanoindentation." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5027.

Full text
Abstract:
Thesis (M.S.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 27, 2008) Includes bibliographical references.
APA, Harvard, Vancouver, ISO, and other styles
7

Fogelson, Benjamin Marc Feder. "Mechanical Models in Single-Cell Locomotion, Adhesion, and Force Production." Thesis, New York University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10190369.

Full text
Abstract:

Here we present the results of two distinct projects in the field of cellular mechanics. In the first project, we describe a non-monotonicity in the scaling of force production in actomyosin stress fibers. We develop a continuum mechanical model to explain that non-monotonicity and, using both analytical and numerical techniques, conclude that the scaling is due to an interaction between different physical lengthscales inherent in the actomyosin force-production system. Using singular perturbation methods, we study the model further to make predictions about the physical conditions under which a cell can break symmetry. In the second project, we explore how lipid flow in the plane of the plasma membrane contributes to membrane translocation during cell migration. By numerically solving the Stokes equations, we quantify the magnitude of the force necessary to generate this flow, and analyze how the presence of transmembrane protein obstacles influences the resulting front-to-rear membrane tension gradient. We make several analytic estimates of the mechanical importance of this membrane tension for cell motility.

APA, Harvard, Vancouver, ISO, and other styles
8

Wróblewska, Liliana. "Refinement of reduced protein models with all-atom force fields." Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/26606.

Full text
Abstract:
Thesis (Ph.D)--Biology, Georgia Institute of Technology, 2008.
Committee Chair: Skolnick, Jeffrey; Committee Member: Fernandez, Facundo; Committee Member: Jordan, King; Committee Member: McDonald, John; Committee Member: Sherrill, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.
APA, Harvard, Vancouver, ISO, and other styles
9

Strukel, Steven E. "Analysis of the command and control network model and linkage mechanism with force evaluation models." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23528.

Full text
Abstract:
Approved for public release; distribution is unlimited
Newly emerging functional area models designed to simulate the activities of individual battlefield operating systems are generating challenging new validation issues for Army analysis. From database to output, these new models require testing against real system performance to insure no significant disparities exist. The Command and Control (C2NET) model is a prototype Command and Control Functional Area Model (C2FAM) and exemplifies this validation challenge. This paper examines the C2NET database, input distributions, and linkage mechanism with a force evaluation model as part of C2NET's continuing validation effort. The nonstationary Poisson process is examined and used to develop hypotheses about input distribution linking the evaluation model's tactical scenario with C2NET's input parameters and existing database. Fuzzy set theory us then examined with applications for using C2NET output as input for an evaluation model. Areas for further research are discussed.
APA, Harvard, Vancouver, ISO, and other styles
10

Ostrom, Sara R. "Parallelization of the Air Force Space Command (AFSPACECOM) satellite motion models." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA269327.

Full text
APA, Harvard, Vancouver, ISO, and other styles
11

Unneland, Kari. "Identification and Order Reduction of Radiation Force Models of Marine Structures." Doctoral thesis, Norwegian University of Science and Technology, Department of Engineering Cybernetics, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2222.

Full text
APA, Harvard, Vancouver, ISO, and other styles
12

van, Heerden T. F. "Force method solution of finite element equilibrium models for plane continua." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239208.

Full text
APA, Harvard, Vancouver, ISO, and other styles
13

McCarter, Brian Raymond. "Experimental Evaluation of Viscous Hydrodynamic Force Models for Autonomous Underwater Vehicles." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50445.

Full text
Abstract:
A comparison of viscous hydrodynamic force models is presented, with application on an autonomous underwater vehicle (AUV). The models considered here are \emph{quasi-steady}, meaning that force is expressed as a function of instantaneous vehicle state. This is in contrast to physical reality, where the force applied to a rigid body moving through a viscous fluid is history-dependent. As a result, the comparison of models is restricted to how well they are able to recreate a force history, rather than how closely they represent the underlying physics. Of the models under consideration, no single model performs significantly better than the others, but several perform worse. Each viscous hydrodynamic force model presented here is expressed as a linear combination of basis functions, which are nonlinear functions of body-relative velocity. The greater dynamical model is presented in a rigid-body framework with six degrees of freedom, with terms which account for inviscid fluid flow, restoring forces due to gravity, and control forces due to actuator motion. The models are selected from several that have been proposed in the literature, which include empirically-derived and physics-based models. Some models assume that the relationship between force and velocity is fundamentally linear or quadratic in nature, or make assumptions about coupled motion. The models are compared by their relative complexities, and also by their ability to reproduce data sets generated from field experiments. The complete dynamical equations are presented for each model, including coefficients suitable for use with the Virginia Tech 690 AUV.
Master of Science
APA, Harvard, Vancouver, ISO, and other styles
14

Ramoneda, Igor M. "Force modeling in surface grinding based on the wheel topography analysis." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/18845.

Full text
APA, Harvard, Vancouver, ISO, and other styles
15

Petersson, Frida, and Charlotte Åkerlund. "Haptic Force Feedback Interaction for Planning in Maxillo-Facial Surgery." Thesis, Linköping University, Department of Science and Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2036.

Full text
Abstract:

New Virtual Reality technologies provide the possibility of widening access to information in data. Haptics, the technology of touch, could be an interesting future aid and have large impact on medical applications. The use of haptic devices allows computer users to use their sense of touch, in order to feel virtual objects with a high degree of realism.

The aim of the thesis is to investigate the potential deployment and the benefits of using haptic force feedback instruments in maxillo-facial surgery. Based on a produced test application, the thesis includes suggested recommendations for future haptic implementations.

At the Department of Maxillo-Facial Surgery, at the Karolinska Hospital in Stockholm, Virtual Reality technologies are used as an aid to a limited extent during the production of physical medical models. The physical medical models are produced with Rapid Prototyping techniques. This process is examined and described in the thesis. Moreover, the future of the physical medical models is outlined, and a future alternative visualizing patient data in 3D and use haptics as an interaction tool, is described. Furthermore, we have examined the present use of haptic technology in medicine, and the benefits of using the technology as an aid for diagnostic and treatment planning.

Based on a presented literature study and an international outlook, we found that haptics could improve the management of medical models. The technology could be an aid, both for physical models as well as for virtual models. We found three different ways of implementing haptics in maxillo-facial surgery. A haptic system could be developed in order to only manage virtual medical models and be an alternative solution to the complete Rapid Prototyping process. A haptic system could serve as a software, handling the image processing and interfacing from a medical scanner to an Rapid Prototyping system. A haptic system could be developed as an alternative interaction tool, which could be implemented as an additional function in currently used image processing software, in order to improve the management of virtual medical models before the Rapid Prototyping process.

An implementation for planning and examination in maxillo-facial surgery, using haptic force feedback interaction, is developed and evaluated. The test implementation is underlying our aim of investigating the potential deployment and the benefits of using haptic force feedback instruments in maxillo-facial surgery.

After discussing the possible future of our implementation and the future of haptic force feedback in maxillo-facial surgery, a recommendation is given as a conclusion of our total work.

APA, Harvard, Vancouver, ISO, and other styles
16

Mildenhall, Peter Thomas. "Mental models of force and motion in 11 to 18 years old." Thesis, University of Manchester, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504535.

Full text
APA, Harvard, Vancouver, ISO, and other styles
17

Berloffa, Gabriella. "Intertemporal allocation of consumption and labour force participation in life-cycle models." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387576.

Full text
APA, Harvard, Vancouver, ISO, and other styles
18

Kessler, John M. (John Michael). "United States Air Force fighter jet maintenance Models : effectiveness of index policies." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82873.

Full text
Abstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2013.
Cataloged from PDF version of thesis. "June 2013."
Includes bibliographical references (pages 107-109).
As some of the most technically complex systems in the world, United States fighter aircraft require a complex logistics system to sustain their reliable operation and ensure that the day-to-day Air Force missions can be satisfied. While there has been a lot of attention among academics and practitioners regarding the study of this complex logistics system, most of the focus has been on availability of spare parts that are indeed essential for the smooth operations of the fighter aircraft. However, in recent years there has been an increasing awareness that maintenance resources are an equally important enabler and should be considered together with inventory issues. The maintenance resources required to repair the fighter aircraft are expensive and therefore limited. Moreover, there are various types of maintenance that compete for the same resources. It .is therefore imperative that the allocation of maintenance resources is done as efficiently as possible. In this thesis, we study two areas of fighter aircraft maintenance that could significantly benefit from improved resource allocation and scheduling strategies. We use quantitative and qualitative data from Air Force data-bases and logistics personnel to develop an innovative modeling framework to capture these challenging maintenance problems. This modeling framework is based on a generalization of the of the well-known multi-armed bandit superprocess problem. Using these models, we develop index policies which provide intuitive, easily implemented, and effective rules for scheduling maintenance activities and allocating maintenance resources. These policies seem to improve on existing best practices within the Air Force, and perform well in extensive data-driven simulated computational experiments. The first area is focused on the challenges of scheduling maintenance for the low observable (stealth) capabilities of the F-22 Raptor, specifically, maintenance of the outer coating of the aircraft that is essential to maintain its radar invisibility. In particular, we generate index policies that efficiently schedule which aircraft should enter low observable maintenance, how long they should be worked on, and which aircraft should fly in order to maximize the stealth capability of the fleet. Secondly, we model the maintenance process of the F100-229 engine, which is the primary propulsion method used in the F-16C/D and F-15E aircraft. In particular, we generate index policies to decide which engines should take priority over others, and whether or not certain components of the engines should be repaired or replaced. The policies address both elective (planned) and unplanned maintenance tasks.
by John M. Kessler.
S.M.
APA, Harvard, Vancouver, ISO, and other styles
19

Ngan, Choi-chik, and 顔才績. "A hidden Markov model approach to force-based contact recognition for intelligent robotic assembly." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31243496.

Full text
APA, Harvard, Vancouver, ISO, and other styles
20

Mateyisi, Mohau Jacob. "Polymer networks with mobile force-applying crosslinks." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6759.

Full text
Abstract:
Thesis (MSc)--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: We construct and study a simple model for an active gel of exible polymer filaments crosslinked by a molecular motor cluster that perform reversible work while translating along the filaments. The filament end points are crosslinked to an elastic background. In this sense we employ a simplified model for motor clusters that act as slipping links that exert force while moving along the strands. Using the framework of replica theory, quenched averages are taken over the disorder which originates from permanent random crosslinking of network end points to the background. We investigate how a small motor force contributes to the elastic properties of the network. We learn that in addition to the normal elastic response for the network there is an extra contribution to the network elasticity from the motor activity. This depends on the ratio of the entropic spring constant for the linked bio-polymerchain to the spring constant of the tether of the motor.
AFRIKAANSE OPSOMMING: Ons konstrueer en bestudeer 'n eenvoudige model vir 'n aktiewe netwerk van eksieble polimeerfilamente wat deur grosse van molekulere motors aan mekaar verbind word wat omkeerbare werk doen terwyl dit langs die filamente transleer. Die eindpunte van die filamente is aan 'n elastiese agtergrond verbind. In hierdie sin benut ons 'n eenvoudige model vir motorclusters wat as verskuifbare verbindings krag op die filamente tydens beweging kan uitoefen. Nie-termiese wanorde gemiddeldes word geneem oor die wanorde wat deur die lukrake permanente verbindings van netwerk eindpunte aan die agtergrond veroorsaak word. Ons ondersoek hoe 'n klein motorkrag tot die elastiese eienskappe van die netwerk bydra. Ons leer dat daar bo en behalwe die gewone elastiese respons vir die netwerk 'n elastiese bydrae as gevolg van die motors se aktiwiteit voorkom. Dit hang af van die verhouding van die entropiese veerkonstante van die biopolimerketting tot die veerkonstante van die anker van die motor.
APA, Harvard, Vancouver, ISO, and other styles
21

Billing, Daniel Charles. "Prediction of ground reaction forces in running from wearable instrumentation and algorithmic models." Swinburne Research Bank, 2006. http://hdl.handle.net/1959.3/38323.

Full text
Abstract:
Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, 2006.
A thesis submitted for the degree of Doctor of Philosophy, [Faculty of Engineering and Industrial Sciences], Swinburne University of Technology, 2006. Typescript. Includes bibliographical references (p. 251-256)
APA, Harvard, Vancouver, ISO, and other styles
22

Zhang, Qiang Mechanical &amp Manufacturing Engineering Faculty of Engineering UNSW. "A study of high performance twist drill design and the associated predictive force models." Awarded by:University of New South Wales. Mechanical and Manufacturing Engineering, 2007. http://handle.unsw.edu.au/1959.4/31220.

Full text
Abstract:
This thesis presents a detailed analysis of the plane rake faced drill design, its grinding method and grinding wheel geometry. A fundamental geometrical analysis has then been carried out on the major cutting edges of the modified drills according to the national and international standards. It has been shown that this new drill design results in a significant increase in the normal rake angle at lips as well as point relieving at the chisel edge region. Geometrical models for the various drill point features have been established which uniquely define the drill point features of the modified drill design. A comprehensive experimental investigation has been carried out to study the drilling performance of the modified drills, when drilling a high tensile steel, ASSAB 4340, with TiN coated high speed steel drills over a wide range of drilling conditions. Comparing to the drilling performance with conventional twist drills under the corresponding conditions, it has been found that the modified drills can reduce the thrust force by as much as 46.9% with the average of 23.8%; the reduction of drilling torque is also significant at an average of 13.2% and the maximum of 24.9%. Similarly, the new drill design shows great superiorities over the conventional drills in terms of drill-life. In the drill-life tests, a few conventional drills were broken, but all plane rake faced drills performed very well. In order to estimate the cutting performance in process planning on a mathematical and quantitative basis when drilling with the modified drills, predictive cutting force models have been developed based on the unified-generalized mechanics of cutting approach. The models have been assessed qualitatively and quantitatively and showed good agreements with the experimental thrust, torque and power. Empirical-type force equations have also been developed to provide simple alternatives for practical applications.
APA, Harvard, Vancouver, ISO, and other styles
23

Bredenkamp, Karen. "Development of biomechanical models that represent members of the South African National Defence Force." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/3227.

Full text
APA, Harvard, Vancouver, ISO, and other styles
24

Yoon, Jongyun. "QUASI-LINEAR DYNAMIC MODELS OF HYDRAULIC ENGINE MOUNT WITH FOCUS ON INTERFACIAL FORCE ESTIMATION." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1281366966.

Full text
APA, Harvard, Vancouver, ISO, and other styles
25

Cardi, Adam A. "On the development of a dynamic cutting force model with application to regenerative chatter in turning." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28152.

Full text
Abstract:
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.
Committee Co-Chair: Bement, Matt; Committee Co-Chair: Liang, Steven; Committee Member: Griffin, Paul; Committee Member: Mayor, Rhett; Committee Member: Melkote, Shreyes; Committee Member: Zhou, Chen.
APA, Harvard, Vancouver, ISO, and other styles
26

Acosta, Jared. "Comparative Hydrodynamic Testing of Small Scale Models." ScholarWorks@UNO, 2008. http://scholarworks.uno.edu/td/864.

Full text
Abstract:
Early in the ship design process, naval architects must often evaluate and compare multiple hull forms for a specific set of requirements. Analytical tools are useful for quick comparisons, but they usually specialize in a specific hull type and are therefore not adequate for comparing dissimilar hull types. Scale model hydrodynamic testing is the traditional evaluation method, and is applicable to most hull forms. Scale model tests are usually performed on the largest model possible in order to achieve the most accurate performance predictions. However, such testing is very resource intensive, and is therefore not a cost effective method of evaluating multiple hull forms. This thesis explores the testing of small scale models. It is hypothesized that although the data acquired by these tests will not be accurate enough for performance predictions, they will be accurate enough to rank the performance of the multiple hull forms being evaluated.
APA, Harvard, Vancouver, ISO, and other styles
27

Cvitkovic, John Peter. "From All-Atom Molecular Mechanics to Coarse- Grained Lattice Models: Computational Approaches to Problems in Protein Biochemistry." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-dissertations/524.

Full text
Abstract:
Computational simulations of chemical systems play an ever-increasing role in many areas of biochemical research from rational drug design to probing fundamental physiological processes. Depending on the method, a vast array of properties are able to be predicted. Here we report the design and implementation of two methods for investigating diverse problems in protein biochemistry. In order to better understand protein–metal interactions—most importantly for the difficult to model transition metal ions— empirical force field parameters were developed for Pt(II), cisplatin, and other Pt(II) coordination compounds. Two force field frameworks were used: a modified version of the fixed- charge OPLS-AA and the polarizable POSSIM force field. A seven-site model was used for the Pt(II) ion. The produced parameters are compatible with the OPLS-AA and POSSIM force fields and can be used in protein–metal binding simulations in which—contrary to the common treatment of metal ions in such simulations—the position or even coordination of the ion does not have to be constrained using preexisting knowledge. It has been demonstrated that the produced models are capable of reproducing key properties of relevant Pt(II) complexes but that the POSSIM formalism yields more accurate values for energies of formation than the OPLS-AA model. This Pt(II) model was employed—along with previously developed Cu(I) parameters—to investigate the binding of platinum to the protein Atox1, a human copper chaperone implicated in the resistance mechanism of cisplatin and other platinum antitumor compounds. In collaboration with the Dmitriev and Bernholc groups, we used our models to inform and refine spectroscopic experiments as well as to serve as starting points for high-performance quantum calculations. It was shown that under physiological redox conditions, copper(I) and cisplatin can form large polymers with glutathione. These polymers were capable of transferring copper(I) to apo-Atox1 or to platinum(II) to copper-loaded Atox1. Analysis of the simultaneous binding of copper(I) and platinum(II) to Atox1 was found to occur through the formation of copper–sulfur–platinum bridges, where copper is coordinated by three sulfur atoms and platinum by four sulfur atoms. With the goal of using a simple model to be able to quickly estimate the acid disassociation constants of proteins, PKA17 has been developed and tested. PKA17 is a coarse-grain grid-based method and software tool for accurately and rapidly calculating protein pKa values given an input PDB structure file. During development, parameter fitting was carried out using a compilation of 442 Asp, Glu, His, and Lys residues that had both high-resolution PDB structures and published experimental pKa values available. Applying our PKA17 model, the calculated average unsigned error and RMSD for the residue set were found to be 0.628 and 0.831 pH units, respectively. As a benchmark for comparison, the same residue set was evaluated with the PROPKA software package which resulted in an average unsigned error of 0.761 pH units and an RMSD of 1.063 pH units. Finally, a web interface for the PKA17 software was developed and deployed (http://users.wpi.edu/~jpcvitkovic/pka_calc.html) to make PKA17 available to the wider scientific community.
APA, Harvard, Vancouver, ISO, and other styles
28

Lin, Tzu-Jen. "Force Field Parameters and Atomistic Surface Models forHydroxyapatite and Analysis of Biomolecular Adsorption at Aqueous Interfaces." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1365511604.

Full text
APA, Harvard, Vancouver, ISO, and other styles
29

Taylor, Dennis James. "Developing a task force to plan worship for urban people utilizing Biblical models of worship." Theological Research Exchange Network (TREN), 1990. http://www.tren.com.

Full text
APA, Harvard, Vancouver, ISO, and other styles
30

Bourouiba, Lydia. "Numerical and theoretical study of homogeneous rotating turbulence." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115861.

Full text
Abstract:
The Coriolis force has a subtle, but significant impact on the dynamics of geophysical and astrophysical flows. The Rossby number, Ro, is the nondimensional parameter measuring the relative strength of the Coriolis term to the nonlinear advection terms in the equations of motion. When the rotation is strong, Ro goes to zero and three-dimensional flows are observed to two-dimensionalize. The broad aim of this work is to examine the effect of the strength of rotation on the nonlinear dynamics of turbulent homogeneous flows. Our approach is to decompose the rotating turbulent flow modes into two classes: the zero-frequency 2-dimensional (2D) modes; and the high-frequency inertial waves (3D).
First, using numerical simulations of decaying turbulence over a large range of Ro we identified three regimes. The large Ro regime is similar to non-rotating, isotropic turbulence. The intermediate Ro regime shows strong 3D-to-2D energy transfers and asymmetry between cyclones (corotating) and anticyclones (couter-rotating), whereas at small Ro regime these features are much reduced.
We then studied discreteness effects and constructed a kinematic model to quantify the threshold of nonlinear broadening below which the 2D-3D interactions critical to the intermediate Ro regime are not captured. These results allow for the improvement of numerical studies of rotating turbulence and refine the comparison between results obtained in finite domains and theoretical results derived in unbounded domains.
Using equilibrium statistical mechanics, we examined the hypothesis of decoupling predicted in the small Ro regime. We identified a threshold time, t☆ = 2/Ro2, after which the asymptotic decoupling regime is no longer valid. Beyond t ☆, we show that the quasi-invariants of the decoupled model continue to constrain the system on the short timescales.
We found that the intermediate Ro regime is also present in forced turbulence and that interactions responsible for it are nonlocal. We explain a steep slope obtained in the 2D energy spectrum by a downscale enstrophy transfer. The energy of the 2D modes is observed to accumulate in the largest scales of the domain in the long-time limit. This is reminiscent of the "condensation" observed in classical forced 2D flows and magnetohydrodynamics.
APA, Harvard, Vancouver, ISO, and other styles
31

Bardizbanian, Berj. "Improving the Performance of Dynamic Electromyogram-to-Force Models for the Hand-Wrist and Multiple Fingers." Digital WPI, 2020. https://digitalcommons.wpi.edu/etd-dissertations/600.

Full text
Abstract:
Relating surface electromyogram (EMG) activity to force/torque models is used in many areas including: prosthesis control systems, to regulate direction and speed of movement in reaching and matching tasks; clinical biomechanics, to assess muscle deficiency and effort levels; and ergonomics analysis, to assess risk of work-related injury such as back pain, fatigue and skill tests. This thesis work concentrated on improving the performance of dynamic EMG-to-force models for the hand-wrist and multiple fingers. My contributions include: 1) rapid calibration of dynamic hand-wrist EMG-force models using a minimum number of electrodes, 2) efficiently training two degree of freedom (DoF) hand-wrist EMG-force models, and 3) estimating individual and combined fingertip forces from forearm EMG during constant-pose, force-varying tasks. My calibration approach for hand-wrist EMG-force models optimized three main factors for 1-DoF and 2-DoF tasks: training duration (14, 22, 30, 38, 44, 52, 60, 68, 76 s), number of electrodes (2 through 16), and model forms (subject-specific, DoF-specific, universal). The results show that training duration can be reduced from historical 76 s to 40–60 s without statistically affecting the average error for both 1-DoF and 2-DoF tasks. Reducing the number of electrodes depended on the number of DoFs. One-DoF models can be reduced to 2 electrodes with average test error range of 8.3–9.2% maximum voluntary contraction (MVC), depending on the DoF (e.g., flexion-extension, radial-ulnar deviation, pronation-supination, open-close). Additionally, 2-DoF models can be reduced to 6 electrodes with average error of 7.17–9.21 %MVC. Subject-specific models had the lowest error for 1-DoF tasks while DoF-specific and universal were the lowest for 2-DoF tasks. In the EMG-finger project, we studied independent contraction of one, two, three or four fingers (thumb excluded), as well as contraction of four fingers in unison. Using regression, we found that a pseudo-inverse tolerance (ratio of largest to smallest singular value) of 0.01 was optimal. Lower values produced erratic models and higher values produced models with higher errors. EMG-force errors using one finger ranged from 2.5–3.8 %MVC, using the optimal pseudoinverse tolerance. With additional fingers (two, three or four), the average error ranged from 5–8 %MVC. When four fingers contracted in unison, the average error was 4.3 %MVC. Additionally, I participated in two team projects—EMG-force dynamic models about the elbow and relating forearm muscle EMG to finger force during slowly force varying contractions. This work is also described herein.
APA, Harvard, Vancouver, ISO, and other styles
32

Gönül, Füsun Feride. "Astructural and structural methods in the estimation of models of labor force participation and search behavior." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1272454788.

Full text
APA, Harvard, Vancouver, ISO, and other styles
33

Gönül, Füsun. "Astructural and structural methods in the estimation of models of labor force participation and search behavior /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487267024995055.

Full text
APA, Harvard, Vancouver, ISO, and other styles
34

Chevrier, Solène. "Development of subgrid models for a periodic circulating fluidized bed of binary mixture of particles." Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/19905/1/CHEVRIER_Solene.pdf.

Full text
Abstract:
Detailed sensitivity numerical studies have shown that the mesh cell-size may have a drastic effect on the modelling of circulating fluidized bed with small particles. Typically, the cell-size must be of the order of few particle diameters to predict accurately the dynamical behaviour of a fluidized bed. Hence, the Euler-Euler numerical simulations of industrial processes are generally performed with grids too coarse to allow the prediction of the local segregation effects. Appropriate modelling, which takes into account the influence of unresolved structures, have been already proposed for monodisperse simulations. In this work, the influence of unresolved structures on a binary mixture of particles is investigated and models are proposed to account for those effect on bidisperse simulations of bidisperse gas-solid fluidized bed. To achieve this goal, Euler-Euler reference simulations are performed with grid refinement up to reach a mesh independent solution. Such kind of numerical simulation is very expensive and is restricted to very simple configurations. In this work, the configuration consists of a 3D periodical circulating fluidized bed, that could represent the established zone of an industrial circulating fluidized bed. In parallel, a filtered approach is developed where the unknown terms, called sub-grid contributions, appear. They correspond to the difference between filtered terms, which are calculated with the reference results then filtered, and resolved contributions, calculated with the filtered fields. Then spatial filters can be applied to reference simulation results to measure each sub-grid contribution appearing in the theoretical filtered approach. A budget analysis is carried out to understand and model the sub-grid term. The analysis of the filtered momentum equation shows that the resolved fluid-particle drag and inter-particle collision are overestimating the momentum transfer effects. The analysis of the budget of the filtered random kinetic energy shows that the resolved production by the mean shear and by the mean particle relative motion are underestimating the filtered ones. Functional models are proposed for the subgrid contributions of the drag and the inter-particle collision.
APA, Harvard, Vancouver, ISO, and other styles
35

Izadi, Saeed. "Optimal Point Charge Approximation: from 3-Atom Water Molecule to Million-Atom Chromatin Fiber." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/81539.

Full text
Abstract:
Atomistic modeling and simulation methods enable a modern molecular approach to bio-medical research. Issues addressed range from structure-function relationships to structure-based drug design. The ability of these methods to address biologically relevant problems is largely determined by their accurate treatment of electrostatic interactions in the target biomolecular structure. In practical molecular simulations, the electrostatic charge density of molecules is approximated by an arrangement of fractional "point charges" throughout the molecule. While chemically intuitive and straightforward in technical implementation, models based exclusively on atom-centered charge placement, a major workhorse of the biomolecular simulations, do not necessarily provide a sufficiently detailed description of the molecular electrostatic potentials for small systems, and can become prohibitively expensive for large systems with thousands to millions of atoms. In this work, we propose a rigorous and generally applicable approach, Optimal Point Charge Approximation (OPCA), for approximating electrostatic charge distributions of biomolecules with a small number of point charges to best represent the underlying electrostatic potential, regardless of the distance to the charge distribution. OPCA places a given number of point charges so that the lowest order multipole moments of the reference charge distribution are optimally reproduced. We provide a general framework for calculating OPCAs to any order, and introduce closed-form analytical expressions for the 1-charge, 2-charge and 3-charge OPCA. We demonstrate the advantage of OPCA by applying it to a wide range of biomolecules of varied sizes. We use the concept of OPCA to develop a different, novel approach of constructing accurate and simple point charge water models. The proposed approach permits a virtually exhaustive search for optimal model parameters in the sub-space most relevant to electrostatic properties of the water molecule in liquid phase. A novel rigid 4-point Optimal Point Charge (OPC) water model constructed based on the new approach is substantially more accurate than commonly used models in terms of bulk water properties, and delivers critical accuracy improvement in practical atomistic simulations, such as RNA simulations, protein folding, protein-ligand binding and small molecule hydration. We also apply our new approach to construct a 3-point version of the Optimal Point Charge water model, referred to as OPC3. OPCA can be employed to represent large charge distributions with only a few point charges. We use this capability of OPCA to develop a multi-scale, yet fully atomistic, generalized Born approach (GB-HCPO) that can deliver up to 2 orders of magnitude speedup compared to the reference MD simulation. As a practical demonstration, we exploit the new multi-scale approach to gain insight into the structure of million-atom 30-nm chromatin fiber. Our results suggest important structural details consistent with experiment: the linker DNA fills the core region and the H3 histone tails interact with the linker DNA. OPC, OPC3 and GB-HCPO are implemented in AMBER molecular dynamics software package.
Ph. D.
APA, Harvard, Vancouver, ISO, and other styles
36

Kane-Sellers, Marjorie Laura. "Predictive models of employee voluntary turnover in a North American professional sales force using data-mining analysis." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1486.

Full text
APA, Harvard, Vancouver, ISO, and other styles
37

Wilson, Fiona. "Equilibrium and stability properties of collisionless current sheet models." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3548.

Full text
Abstract:
The work in this thesis focuses primarily on equilibrium and stability properties of collisionless current sheet models, in particular of the force-free Harris sheet model. A detailed investigation is carried out into the properties of the distribution function found by Harrison and Neukirch (Physical Review Letters 102, 135003, 2009) for the force-free Harris sheet, which is so far the only known nonlinear force-free Vlasov-Maxwell equilibrium. Exact conditions on the parameters of the distribution function are found, which show when it can be single or multi-peaked in two of the velocity space directions. This is important because it may have implications for the stability of the equilibrium. One major aim of this thesis is to find new force-free equilibrium distribution functions. By using a new method which is different from that of Harrison and Neukirch, it is possible to find a complete family of distribution functions for the force-free Harris sheet, which includes the Harrison and Neukirch distribution function (Physical Review Letters 102, 135003, 2009). Each member of this family has a different dependence on the particle energy, although the dependence on the canonical momenta remains the same. Three detailed analytical examples are presented. Other possibilities for finding further collisionless force-free equilibrium distribution functions have been explored, but were unsuccessful. The first linear stability analysis of the Harrison and Neukirch equilibrium distribution function is then carried out, concentrating on macroscopic instabilities, and considering two-dimensional perturbations only. The analysis is based on the technique of integration over unperturbed orbits. Similarly to the Harris sheet case (Nuovo Cimento, 23:115, 1962), this is only possible by using approximations to the exact orbits, which are unknown. Furthermore, the approximations for the Harris sheet case cannot be used for the force-free Harris sheet, and so new techniques have to be developed in order to make analytical progress. Full analytical expressions for the perturbed current density are derived but, for the sake of simplicity, only the long wavelength limit is investigated. The dependence of the stability on various equilibrium parameters is investigated.
APA, Harvard, Vancouver, ISO, and other styles
38

Golinucci, Luca. "Lateral tires characterization: testing, analytical models and applications for aeronautic purpose." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/6097/.

Full text
Abstract:
The lateral characteristics of tires in terms of lateral forces as a function of sideslip angle is a focal point in the prediction of ground loads and ground handling aircraft behavior. However, tests to validate such coefficients are not mandatory to obtain Aircraft Type Certification and so they are not available for ATR tires. Anyway, some analytical values are implemented in ATR calculation codes (Flight Qualities in-house numerical code and Loads in-house numerical code). Hence, the goal of my work is to further investigate and validate lateral tires characteristics by means of: exploitation and re-parameterization of existing test on NLG tires, implementation of easy-handle model based on DFDR parameters to compute sideslip angles, application of this model to compute lateral loads on existing flight tests and incident cases, analysis of results. The last part of this work is dedicated to the preliminary study of a methodology to perform a test to retrieve lateral tire loads during ground turning with minimum requirements in terms of aircraft test instrumentation. This represents the basis for future works.
APA, Harvard, Vancouver, ISO, and other styles
39

Song, Wenge. "Development of predictive force models for classical orthogonal and oblique cutting and turning operations incorporating tool flank wear effects." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16239/1/Wenge_Song_Thesis.pdf.

Full text
Abstract:
Classical orthogonal and oblique cutting are the fundamental material removal or machining processes to which other practical machining processes can be related in the study and modelling of the machining processes. In the last century, a large amount of research and development work has been done to study and understand the various machining processes with a view to improving the processes for further economic (cost and productivity) gains. However, many aspects of the cutting processes and cutting performance remains to be fully understood in order to increase the cutting capability and optimize the cutting processes; in particular, there is little study to understand the effects of the inevitable tool wear on the machining processes. This thesis includes an extensive literature review on the mechanics of cutting analysis. Considerable work has been carried out in past decades on the fundamental analysis of 'sharp' tool cutting. Although some work has been reported on the effects of tool flank wear on the cutting performance, there is a general lack of the fundamental study of the effects of the flank wear on the basic cutting or chip formation process. It has been well documented that tool flank wear results in an increase in the cutting forces. However, it was not known if this force increase is a result of the change in the chip formation process, and/or the rubbing or ploughing forces between the tool flank and the workpiece. In work carried out since the early 1980s, the effects of the so-called edge forces have been considered when the tool is not absolutely sharp. Little has been reported to further develop fundamental cutting theories to understand applications to more relevant the practical situation, i.e. to consider the tool wear effects. Based on the findings of the literature review, an experimental investigation is presented in the first part of the thesis to study the effects of tool flank wear on the basic cutting or chip formation process by examining the basic cutting variables and performance in the orthogonal cutting process with tool flank wear. The effects of tool flank wear on the basic cutting variables are discussed by a comprehensive analysis of the experimental data. It has been found that tool flank wear does not affect the basic cutting variables (i.e. shear angle, friction angle and shear stress). It is therefore deduced that the flank wear does not affect the basic chip formation process in the shear zone and in the tool-chip interface. The study also finds that tool flank wear causes an increase in the total cutting forces, as can be expected and such an increase is entirely a result of the rubbing or ploughing forces on the tool wearland. The significance of this finding is that the well-developed machining theories for 'sharp' tools can be used in modelling the machining processes when tool flank wear is present, rather than study the machining process and develop machining theories from scratch. The ploughing forces can be modelled for incorporation into the overall cutting force prediction. The experimental study also allows for the forces on the wearland (or wearland force) and edge forces to be separated from the total measured forces. The wearland force and edge force models are developed in empirical form for force prediction purpose. In addition, a database for the basic cutting variables or quantities is established for use in modelling the cutting forces. The orthogonal cutting force model allowing for the effects of flank wear is developed and verified by the experimental data. A comprehensive analysis of the mechanics of cutting in the oblique cutting process is then carried out. Based on this analysis, predictive cutting force models for oblique cutting allowing for the effects of flank wear are proposed. The wearland force and edge force are re-considered by analysing the oblique cutting process and the geometrical relation. The predictive force models are qualitatively and quantitatively assessed by oblique cutting tests. It shows that the model predictions are in excellent agreement with the experimental data. The modelling approach is then used to develop the cutting force models for a more general machining process, turning operation. By using the concept of an equivalent cutting edge, the tool nose radius is allowed for under both orthogonal and oblique cutting conditions. The wearland forces and edge forces are taken into consideration by the integration of elemental forces on the tool flank and the cutting edge, respectively. The cutting forces in turning operations are successfully predicted by using the basic cutting quantity database established in the orthogonal cutting analysis. The models are verified by turning operation tests. It shows that the model predictions are in excellent agreement with the experimental results both qualitatively and quantitatively. The major findings, research impacts and practical implications of the research are finally highlighted in the conclusion. The modelling approach considering the flank wear effects in the classical orthogonal and oblique cutting and turning operations can be readily extended to other machining operations, such as drilling and milling.
APA, Harvard, Vancouver, ISO, and other styles
40

Song, Wenge. "Development of predictive force models for classical orthogonal and oblique cutting and turning operations incorporating tool flank wear effects." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16239/.

Full text
Abstract:
Classical orthogonal and oblique cutting are the fundamental material removal or machining processes to which other practical machining processes can be related in the study and modelling of the machining processes. In the last century, a large amount of research and development work has been done to study and understand the various machining processes with a view to improving the processes for further economic (cost and productivity) gains. However, many aspects of the cutting processes and cutting performance remains to be fully understood in order to increase the cutting capability and optimize the cutting processes; in particular, there is little study to understand the effects of the inevitable tool wear on the machining processes. This thesis includes an extensive literature review on the mechanics of cutting analysis. Considerable work has been carried out in past decades on the fundamental analysis of 'sharp' tool cutting. Although some work has been reported on the effects of tool flank wear on the cutting performance, there is a general lack of the fundamental study of the effects of the flank wear on the basic cutting or chip formation process. It has been well documented that tool flank wear results in an increase in the cutting forces. However, it was not known if this force increase is a result of the change in the chip formation process, and/or the rubbing or ploughing forces between the tool flank and the workpiece. In work carried out since the early 1980s, the effects of the so-called edge forces have been considered when the tool is not absolutely sharp. Little has been reported to further develop fundamental cutting theories to understand applications to more relevant the practical situation, i.e. to consider the tool wear effects. Based on the findings of the literature review, an experimental investigation is presented in the first part of the thesis to study the effects of tool flank wear on the basic cutting or chip formation process by examining the basic cutting variables and performance in the orthogonal cutting process with tool flank wear. The effects of tool flank wear on the basic cutting variables are discussed by a comprehensive analysis of the experimental data. It has been found that tool flank wear does not affect the basic cutting variables (i.e. shear angle, friction angle and shear stress). It is therefore deduced that the flank wear does not affect the basic chip formation process in the shear zone and in the tool-chip interface. The study also finds that tool flank wear causes an increase in the total cutting forces, as can be expected and such an increase is entirely a result of the rubbing or ploughing forces on the tool wearland. The significance of this finding is that the well-developed machining theories for 'sharp' tools can be used in modelling the machining processes when tool flank wear is present, rather than study the machining process and develop machining theories from scratch. The ploughing forces can be modelled for incorporation into the overall cutting force prediction. The experimental study also allows for the forces on the wearland (or wearland force) and edge forces to be separated from the total measured forces. The wearland force and edge force models are developed in empirical form for force prediction purpose. In addition, a database for the basic cutting variables or quantities is established for use in modelling the cutting forces. The orthogonal cutting force model allowing for the effects of flank wear is developed and verified by the experimental data. A comprehensive analysis of the mechanics of cutting in the oblique cutting process is then carried out. Based on this analysis, predictive cutting force models for oblique cutting allowing for the effects of flank wear are proposed. The wearland force and edge force are re-considered by analysing the oblique cutting process and the geometrical relation. The predictive force models are qualitatively and quantitatively assessed by oblique cutting tests. It shows that the model predictions are in excellent agreement with the experimental data. The modelling approach is then used to develop the cutting force models for a more general machining process, turning operation. By using the concept of an equivalent cutting edge, the tool nose radius is allowed for under both orthogonal and oblique cutting conditions. The wearland forces and edge forces are taken into consideration by the integration of elemental forces on the tool flank and the cutting edge, respectively. The cutting forces in turning operations are successfully predicted by using the basic cutting quantity database established in the orthogonal cutting analysis. The models are verified by turning operation tests. It shows that the model predictions are in excellent agreement with the experimental results both qualitatively and quantitatively. The major findings, research impacts and practical implications of the research are finally highlighted in the conclusion. The modelling approach considering the flank wear effects in the classical orthogonal and oblique cutting and turning operations can be readily extended to other machining operations, such as drilling and milling.
APA, Harvard, Vancouver, ISO, and other styles
41

Veiga, Alinne de Carvalho. "Methods for analysing complex panel data using multilevel models with an application to the Brazilian labour force survey." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/166583/.

Full text
Abstract:
Data sets commonly used in the social sciences are often obtained by sample surveys with complex designs. These designs usually incorporate a multistage selection from a population with a natural hierarchical structure. In addition, these surveys can also be carried out in a repeated manner including a rotating panel design, which is a source of planned non-response. Unplanned non-response is also present in panel data in the form of panel attrition and intermittent nonresponse. Methods are developed to handle this type of data complexity. These methods follow the Multilevel Model framework which is reviewed. Longitudinal growth curve models accounting for the complex data hierarchy are tted. Recognizing the need to account for the complex correlation structure present in the data, multivariate multilevel models are then adopted. Alternative modied correlation structures accounting for the rotating sample design are proposed. Multivariate multilevel models are tted utilizing these alternative correlation structures. In addition, models estimated using robust methods are compared with those estimated using standard methods. A method for calculating a set of longitudinal sample weights that accounts for attrition is proposed. Models utilising the conditional sample weights and longitudinal weights are tted using the Probability-weighted Iterative Generalized Least Squares (PWIGLS) estimation method. Furthermore, an extension to PWIGLS for multivariate multilevel models is developed. Models tted through dierent estimation methods are compared and the best approaches are suggested. Data from the Brazilian labour force survey, Pesquisa Mensal de Emprego (PME) are used. The PME has a complex sampling design that includes a multistage selection of the sample units and a rotating panel design characterised as 4-8-4. The methods developed are used to investigate the labour income dynamics of employed heads of households in the PME survey.
APA, Harvard, Vancouver, ISO, and other styles
42

Eynon, James R. "Comparison of Logistic Force of Mortality Models for Predicting Life Table Probabilities of Death: A Simulation-Based Approach." Youngstown State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1329508121.

Full text
APA, Harvard, Vancouver, ISO, and other styles
43

Lindquist, Joseph M. "An analysis of degraded communications in the Army's future force." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FLindquist.pdf.

Full text
APA, Harvard, Vancouver, ISO, and other styles
44

Roithmayr, Carlos. "Relating constrained motion to force through Newton's second law." Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-03302007-125659/.

Full text
Abstract:
Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2007.
Bauchau, Olivier, Committee Member ; Hodges, Dewey, Committee Chair ; Singhose, William, Committee Member ; Costello, Mark, Committee Member ; Flannery, Raymond, Committee Member.
APA, Harvard, Vancouver, ISO, and other styles
45

Wu, Jingshu. "Direct simulation of flexible particle suspensions using lattice-boltzmann equation with external boundary force." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33858.

Full text
Abstract:
Determination of the relation between the bulk or rheological properties of a particle suspension and its microscopic structure is an old and important problem in physical science. In general, the rheology of particle suspension is quite complex, and the problem becomes even more complicated if the suspending particle is deformable. Despite these difficulties, a large number of theoretical and experimental investigations have been devoted to the analysis and prediction of the rheological behavior of particle suspensions. However, among these studies there are very few investigations that focus on the role of particle deformability. A novel method for full coupling of the fluid-solid phases with sub-grid accuracy for the solid phase is developed. In this method, the flow is computed on a fixed regular 'lattice' using the lattice Boltzmann method (LBM), where each solid particle, or fiber, is mapped onto a Lagrangian frame moving continuously through the domain. The motion and orientation of the particle are obtained from Newtonian dynamics equations. The deformable particle is modeled by the lattice-spring model (LSM).The fiber deformation is calculated by an efficient flexible fiber model. The no-slip boundary condition at the fluid-solid interface is based on the external boundary force (EBF) method. This method is validated by comparing with known experimental and theoretical results. The fiber simulation results show that the rheological properties of flexible fiber suspension are highly dependent on the microstructural characteristics of the suspension. It is shown that fiber stiffness (bending ratio BR) has strong impact on the suspension rheology in the range BR < 3. The relative viscosity of the fiber suspension under shear increases significantly as BR decreases. Direct numerical simulation of flexible fiber suspension allows computation of the primary normal stress difference as a function of BR. These results show that the primary normal stress difference has a minimum value at BR ∼ 1. The primary normal stress differences for slightly deformable fibers reaches a minimum and increases significantly as BR decreases below 1. The results are explained based on the Batchelor's relation for non-Brownian suspensions. The influence of fiber stiffness on the fiber orientation distribution and orbit constant is the major contributor to the variation in rheological properties. A least-squares curve-fitting relation for the relative viscosity is obtained for flexible fiber suspension. This relation can be used to predict the relative viscosity of flexible fiber suspension based on the result of rigid fiber suspension. The unique capability of the LBM-EBF method for sub-grid resolution and multiscale analysis of particle suspension is applied to the challenging problem of platelet motion in blood flow. By computing the stress distribution over the platelet, the "blood damage index" is computed and compared with experiments in channels with various geometries [43]. In platelet simulation, the effect of 3D channel geometry on the platelet activation and aggregation is modeled by using LBM-EBF method. Comparison of our simulations with Fallon's experiments [43] shows a similar pattern, and shows that Dumont's BDI model [40] is more appropriate for blood damage investigation. It has been shown that channels with sharp transition geometry will have larger recirculation areas with high BDI values. By investigating the effect of hinge area geometry on BDI value, we intend to use this multiscale computational method to optimize the design of Bileaflet mechanical heart valves. Both fiber simulations and platelet simulations have shown that the novel LBM-EBF method is more efficient and stable compare to the conventional numerical methods. The new EBF method is a two-Cway coupling method with sub-grid accuracy which makes the platelet simulations possible. The LBM-EBF is the only method to date, to the best of author's knowledge, that can simulate suspensions with large number of deformable particles under complex flow conditions. It is hoped that future researchers may benefit from this new method and the algorithms developed here.
APA, Harvard, Vancouver, ISO, and other styles
46

Martin, Ramaldo S. "Implementation and validation of a computational model of the feline forelimb." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50293.

Full text
Abstract:
Postural control incorporates multiple neural and mechanical systems at various levels of the motor control system, yet the question of how all these systems interact remains unanswered. This dissertation describes development of a biologically based, three-dimensional mathematical model of the forelimb of the domestic cat that integrates skeletal anatomy, muscular architecture, and neural control. Previous work has shown that muscle architecture profoundly affects its function. However, even though the forelimbs of quadrupeds contribute to posture and locomotion differently from hindlimbs, most models of quadruped motion are based upon hindlimb mechanics. The proposed work consists of three main steps: (1) architectural and anatomical characterization, which involves acquisition of muscle attachment data, measurement of whole muscle and muscle fiber properties, and estimation of limb kinematic parameters; (2) model development and implementation, wherein the data will be integrated into a mathematical model using special-purpose software; and (3) model validation, including verification of model estimates against experimentally obtained measurements of muscle moment arms, and prediction of limb kinetics, namely end-point forces arising from perturbations to the limb. It was found that the forelimb does indeed possess structure, particularly at the shoulder and antebrachium, that allows for more diverse movements. The neural wiring in these regions is more complex than in the hindlimb, and there exists substantial muscular structure in place for non-sagittal motion and object suppression and retrieval. Other results showed that the kinematics of the limb alone produce a restorative response to postural disturbance but that the magnitude is reduced, indicating that neural input acts as a modulatory influence on top of the intrinsic mechanism of limb architecture. Furthermore the model demonstrated many of the essential features found in the experiments. This study represents the implementation of the first forelimb model of the cat incorporating mechanical properties and serves as a key component of a full quadruped model to explore posture and locomotion.
APA, Harvard, Vancouver, ISO, and other styles
47

Conaway, Matthew James. "A theory of calcium dynamics in generating force and low-frequency fatigue in paralyzed human soleus." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/656.

Full text
Abstract:
Paralyzed muscle fatigues more quickly than intact muscle. The reason for this difference is currently unknown. This work will bridge this gap in knowledge by evaluating the predictive abilities of higher-resolution closed-form mathematical models of muscle force and fatigue. Knowledge garnered from this effort will suggest possible mechanisms for the differences in fatiguability of muscle in different states of health. The hypothesis to be tested is that the concept missing from present models, and thus the present understanding of the physiology, is the dynamic behavior of divalent calcium (Ca2+) during induced muscle contraction. If the behavior of Ca2+ can be understood as a Riccati-Bass diffusion process, muscle force and low-frequency fatigue in paralyzed muscle can be more accurately predicted over the time course of response to neuromuscular electrical stimulation. The abilities of existing mathematical models to predict force and low-frequency fatigue are compared to the predictive abilities of new models that include the Riccati-Bass equation. There are several major findings of this study. First, it was found that the structure of the Conaway models better predicts force and low-frequency fatigue than do the Ding models. Second, the cross-bridge friction is the most influential factor in generating force in fresh muscle at frequencies greater than 5 pps. Finally, the calcium leak current is most influential in low-frequency fatigue in paralyzed muscle. It is concluded that the process of muscle fatigue occurs as calcium channel remodeling and inactivation of excitation-contraction coupling from ionic crowding accelerate with every additional contraction.
APA, Harvard, Vancouver, ISO, and other styles
48

Alirezaye-Davatgar, Mohammad Taghi Graduate School of Biomedical Engineering Faculty of Engineering UNSW. "Numerical simulation of blood flow in the systemic vasculature incorporating gravitational force with application to the cerebral circulation." Awarded by:University of New South Wales. Graduate School of Biomedical Engineering, 2006. http://handle.unsw.edu.au/1959.4/26177.

Full text
Abstract:
Background. Extensive studies have been conducted to simulate blood flow in the human vasculature using nonlinear equations of pulsatile flow in collapsible tube plus a network of vessels to represent the whole vasculature and the cerebral circulation. For non-linear models numerical solutions are obtained for the fluid flow equations. Methods. Equations of fluid motion in collapsible tubes were developed in the presence of gravitational force (Gforce). The Lax-Wendroff and MacCormack methods were used to solve the governing equations and compared both in terms of accuracy, convergence, and computer processing (CPU) time. A modified vasculature of the whole body and the cerebral circulation was developed to obtain a realistic simulation of blood flow under different conditions. The whole body vasculature was used to validate the simulation in terms of input impedance and wave transmission. The cerebral vasculature was used to simulate conditions such as presence of G-force, blockage of Internal Carotid Artery (ICA), and the effects on cerebral blood flow of changes in mean and pulse pressure. Results. The simulation results for zero G-force were in very good agreement with published experimental data as was the simulation of cerebral blood flow. Both numerical methods for solutions of governing equations gave similar results for blood flow simulations but differed in calculation performance and stability depending on levels of G-force. Simulation results for uniform and sinusoidal G-force are also in good agreement with published experimental results, Blood flow was simulated in the presence of a single (left) carotid artery obstruction with varying morphological structures of the Circle of Willis (CoW). This simulation showed significant differences in contralateral blood flow in the presence or absence of communicating arteries in the CoW. It also was able to simulate the decreases in blood flow in the cerebral circulation compartment corresponding to the visual cortex in the presence of G-force. This is consistent with the known loss of vision under increased acceleration. Conclusions. This study has shown that under conditions of gravitational forces physiological changes in blood flow in the systemic and cerebral vasculature can be simulated realistically by solving the one-dimentional fluid flow equations and non-linear vascular properties numerically. The simulation was able to predict changes in blood flow with different configurations and properties of the vascular network.
APA, Harvard, Vancouver, ISO, and other styles
49

Davis, James D. "An appraisal of cost-effectiveneess (i.e. effectiveness) models used in the Air Force and Navy aircraft engine Component Improvement Programs." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/27991.

Full text
APA, Harvard, Vancouver, ISO, and other styles
50

Deng, Tian. "LES combined with statistical models of spray formation closely to air-blast atomizer." Thesis, Ecully, Ecole centrale de Lyon, 2011. http://www.theses.fr/2011ECDL0037/document.

Full text
Abstract:
Cette thèse présente une extension de l'approche stochastique de l'atomisation primaire de type air assisté près d'un injecteur. Cette approche avait déjà été introduite dans les publications de Gorokhovski et al. Dans le cadre de la simulation des grandes échelles, la zone d'atomisation primaire est simulée comme un corps immergé avec une structure stochastique. Ce dernier est défini par la simulation stochastique de la position et de la courbure de l'interface entre le liquide et le gaz. La simulation de la position de l'interface est basée sur l'hypothèse de symétrie d'échelle pour la fragmentation. La normale extérieure à l'interface est modélisée en supposant une relaxation statistique vers l'isotropie. Les statistiques de la force du corps immergé servent de conditions aux limites pour le champ de vitesse issu de la LES ainsi que pour la production des gouttes de l'atomisation primaire. Celles-ci sont ensuite transportées par une approche lagrangienne. Les collisions entre les gouttes dans la zone d'atomisation primaire sont prises en compte par analogie avec l'approche standard de la théorie cinétique des gaz. Une fermeture est proposée pour la température statistique des gouttelettes. Cette approche est validée par des comparaisons avec les mesures expérimentales de la thèse de Hong. Les résultats numériques pour la vitesse et de la taille des gouttes dans le spray à différentes distances du centre du jet et de l'orifice de la buse sont relativement proches des résultats expérimentaux. Différentes conditions d'entrée pour la vitesse sont testées et comparées aux résultats expérimentaux. Par ailleurs, le rôle spécifique de la zone de recirculation devant le dard liquide est soulignée par le battement du dard liquide et la production de gouttelettes
This thesis introduced an extension to stochastic approach for simulation of air-blast atomization closely to injector. This approach was previously proposed in publications of Gorokhovski with his PHD students. Our extension of this approach is as follows. In the framework of LES approach, the contribution of primary atomization zone is simulated as an immersed solid body with stochastic structure. The last one is defined by stochastic simulation of position-and-curvature of interface between the liquid and the gas. As it was done previously in this approach, the simulation of the interface position was based on statistical universalities of fragmentation under scaling symmetry. Additionally to this, we simulate the outwards normal to the interface, assuming its stochastic relaxation to isotropy along with propagation of spray in the down-stream direction. In this approach, the statistics of immersed body force plays role of boundary condition for LES velocity field, as well as for production of primary blobs, which are then tracked in the Lagrangian way. In this thesis, the inter-particle collisions in the primary atomisation zone are accounted also by analogy with standard kinetic approach for the ideal gas. The closure is proposed for the statistical temperature of droplets. The approach was assessed by comparison with measurements of Hong in his PHD. The results of computation showed that predicted statistics of the velocity and of the size in the spray at different distances from the center plane, at different distances from the nozzle orifice, at different inlet conditions (different gas velocity at constant gas-to-liquid momentum ratio, different gas-to-liquid momentum ratio) are relatively close to measurements. Besides, the specific role of recirculation zone in front of the liquid core was emphasized in the flapping of the liquid core and in the droplets production
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the bibliographies on the topic 'Force models' for other source types:
Journal articles Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography