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Articles 691 - 720 of 824

Full-Text Articles in Physical Sciences and Mathematics

Simulation, Kriging, And Visualization Of Circular-Spatial Data, William James Morphet May 2009

Simulation, Kriging, And Visualization Of Circular-Spatial Data, William James Morphet

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The circular dataimage is defined by displaying direction as the color at the same direction in a color wheel composed of a sequence of two-color gradients with color continuity between gradients. The resulting image of circular-spatial data is continuous with high resolution. Examples include ocean wind direction, Earth's main magnetic field, and rocket nozzle internal combustion flow. The cosineogram is defined as the mean cosine of the angle between random components of direction as a function of distance between observation locations. It expresses the spatial correlation of circular-spatial data. A circular kriging solution is developed based on a model fitted …


A Method For Introducing Artificial Perception (Ap) To Improve Human Behavior Representation (Hbr) Using Agents In Synthetic Environments, Randall Bartholomew Garrett Apr 2009

A Method For Introducing Artificial Perception (Ap) To Improve Human Behavior Representation (Hbr) Using Agents In Synthetic Environments, Randall Bartholomew Garrett

Computational Modeling & Simulation Engineering Theses & Dissertations

While psychology has shown that perception is very important for the human decision process, agent perception has not been covered in sufficient detail within the agent directed simulation field. To contribute to such a solution, an open challenge lies in capturing the knowledge of human sciences, such as psychology, and making this knowledge usable for engineers. This dissertation addresses perception by describing an experimental method where agent perception simulates human perception. In particular, it presents engineering methods based on accepted psychological approaches resulting in a proof of concept. To prove the feasibility, an Artificial Perception (AP) meta-model is presented using …


Simulations In 3d Tactics, Interdiction And Multi-Agent Modelling, A. R. Green, I. C. Piper, Daniel Keep, C. J. Flaherty Jan 2009

Simulations In 3d Tactics, Interdiction And Multi-Agent Modelling, A. R. Green, I. C. Piper, Daniel Keep, C. J. Flaherty

Faculty of Informatics - Papers (Archive)

The analysis of vulnerabilities in large complex spaces is fundamentally problematic. The lack of capacity to generate a threat assessment merely exacerbates this problem. Lacking as well, in current literature is a developed methodology. To overcome this problem, we propose an approach using multi-agent modelling, which is also melded with three dimensional (3D) tactical understandings. Our approach builds on a microsimulation decision support tool, which was developed for a behavioural simulation of CBRN events. Microsimulation is based on the individual; who as an individual has a number of attributes, and which are stochastic (when repeated within an attribute). This approach …


A Simulation Study On The Energy Efficiency Of Pure And Slotted Aloha Based Rfid Tag Reading Protocols, Alejandro Ruiz-Rivera, Dheeraj Klair, Kwan-Wu Chin Jan 2009

A Simulation Study On The Energy Efficiency Of Pure And Slotted Aloha Based Rfid Tag Reading Protocols, Alejandro Ruiz-Rivera, Dheeraj Klair, Kwan-Wu Chin

Faculty of Informatics - Papers (Archive)

This paper studies the energy efficiency of twelve Pure and Slotted Aloha tag reading protocol variants via simulation. We compare their energy consumption in three collision resolution phases: 1) success, 2) collision, and 3) idle. Our extensive simulation results show that Pure Aloha with fast mode and muting has the lowest energy consumption, and hence is most suited for deployment in energy-constrained environments.


An Ontology-Based Simulation Model Exploring The Social Contexts Of Psychostimulant Use Among Young Australians, Pascal Perez, Anne Dray, Paul Dietze, David Moore, Rebecca Jenkinson, Christine Siokou, Rachael Green, Susan L. Hudson, Lisa Maher, Gabriele Bammer Jan 2009

An Ontology-Based Simulation Model Exploring The Social Contexts Of Psychostimulant Use Among Young Australians, Pascal Perez, Anne Dray, Paul Dietze, David Moore, Rebecca Jenkinson, Christine Siokou, Rachael Green, Susan L. Hudson, Lisa Maher, Gabriele Bammer

SMART Infrastructure Facility - Papers

The principal anthropogenic factors driving reef degradation have been known for years, if not decades. Overfishing, sedimentation and nutrient loads are just some of the key impacts of human activities in and around reef communities. Therefore, the future of reefs does not rely on generating new knowledge, but rather on implementing and integrating the knowledge we already have. This will require creating effective links between researchers, managers and communities to promote mutual learning, negotiation and collaborative action for reef management. Combining agent-based models and role-play games, through a technique known as Companion Modelling (ComMod), creates a dynamic and interactive setting …


Variance-Mean Relationships To Analyze Large Survey Data With Application To Health Expenditure Data, Wenli Luo Jan 2009

Variance-Mean Relationships To Analyze Large Survey Data With Application To Health Expenditure Data, Wenli Luo

Legacy Theses & Dissertations (2009 - 2024)

A great deal of work has been done in cost analysis in the last several decades. However, relatively little has been done to learn how efficiently to address the relationship between the variance and mean of the response distribution and how this will affect the choice of an appropriate generalized linear model.


A Software Framework For The Design, Testing And Deployment Of Control Systems For Autonomous Robotics, Duane Stanley Bolick Jr. Jan 2009

A Software Framework For The Design, Testing And Deployment Of Control Systems For Autonomous Robotics, Duane Stanley Bolick Jr.

Browse all Theses and Dissertations

Simulation and control of robotic agents are common enough tasks among computer science and engineering researchers that there exists a large variety of software applications, toolkits, and programming frameworks designed to facilitate such research. The intent of this project is to provide an autonomous robotics simulation and control framework with sufficiently useful tools and reference implementations so as to be immediately useful to basic users, as well as easily understood and extended by software developers and robotics researchers.

As such, this document describes the implementation of a general networking toolkit, an autonomous robotics extension framework, and an autonomous robotics simulator …


Measurement And Simulation Of Laser-Induced Fluorescence From Nonequilibrium Ultracold Neutral Plasmas, A. Denning, Scott D. Bergeson, F. Robicheaux Jan 2009

Measurement And Simulation Of Laser-Induced Fluorescence From Nonequilibrium Ultracold Neutral Plasmas, A. Denning, Scott D. Bergeson, F. Robicheaux

Faculty Publications

We report measurements and simulations of laser-induced fluorescence in ultracold neutral plasmas. We focus on the earliest times, when the plasma equilibrium is evolving and before the plasma expands. In the simulation, the ions interact via the Yukawa potential in a small cell with wrapped boundary conditions. We solve the optical Bloch equation for each ion in the simulation as a function of time. Both the simulation and experiment show the initial increase in ion fluorescence, disorder-induced heating, and coherent oscillation of the rms ion velocity. Detailed modeling of the fluorescence signal makes it possible to use fluorescence spectroscopy to …


Simulation Of Boundary Layer Trajectory Dispersion Sensitivity To Soil Moisture Conditions: Mm5 And Noah-Based Investigation, Rezaul Mahmood Jan 2009

Simulation Of Boundary Layer Trajectory Dispersion Sensitivity To Soil Moisture Conditions: Mm5 And Noah-Based Investigation, Rezaul Mahmood

School of Natural Resources: Faculty Publications

No abstract provided.


Sensitivity Analysis Framework For Large And Complex Simulation Models, Ghaith Rabadi, Shannon Bowling, Charles Keating, Resit Unal Jan 2009

Sensitivity Analysis Framework For Large And Complex Simulation Models, Ghaith Rabadi, Shannon Bowling, Charles Keating, Resit Unal

Engineering Management & Systems Engineering Faculty Publications

In this paper, a framework for conducting Sensitivity Analysis (SA) on large and complex simulation models is introduced. The framework consists of components that are designed to make the SA a systematic process that is easy to manage and follow by simulation analysts and practitioners. Unlike local SA (one-variable-at-a-time SA), the method presented here is variance-based and it is rooted in the field of Design of Experiments (DoE) where Input Variables are varied and Output Variables are measured. Based on the DoE results, a risk scoring system is developed to identify the sensitivity of the Input Variables, and as a …


Bayesian Approach To Average Power Calculations For Binary Regression Models With Misclassified Outcomes, Dunlei Cheng, James D. Stamey, Adam J. Branscum Dec 2008

Bayesian Approach To Average Power Calculations For Binary Regression Models With Misclassified Outcomes, Dunlei Cheng, James D. Stamey, Adam J. Branscum

Dunlei Cheng

We develop a simulation-based procedure for determining the required sample size in binomial regression risk assessment studies when response data are subject to misclassification. A Bayesian average power criterion is used to determine a sample size that provides high probability, averaged over the distribution of potential future data sets, of correctly establishing the direction of association between predictor variables and the probability of event occurrence. The method is broadly applicable to any parametric binomial regression model including, but not limited to, the popular logistic, probit, and complementary log-log models. We detail a common medical scenario wherein ascertainment of true disease …


Hybrid Bond-Order Potential For Silicon, Suleiman Oloriegbe Dec 2008

Hybrid Bond-Order Potential For Silicon, Suleiman Oloriegbe

All Dissertations

ABSTRACT
A new hybrid bond-order potential for silicon is developed. The functional form of the potential is derived from hybrid of expressions from empirical bond-order formalism and first principles approximations. The total energy is expressed as the sum of attractive, repulsive and promotion energies. By introducing a screening function derived from approximations to first principles expressions, the potential is made long-ranged by allowing covalent interactions beyond the first nearest neighbor shell of atoms in agreement with quantum mechanical descriptions of the bonding in silicon. Environment-dependent promotion energy is introduced that accurately accounts for energetic interactions due to changes in hybridization …


Protecting Critical Infrastructure With Games Technology, Adrian Boeing, Martin Masek, Bill Bailey Dec 2008

Protecting Critical Infrastructure With Games Technology, Adrian Boeing, Martin Masek, Bill Bailey

Australian Information Warfare and Security Conference

It is widely recognised that there is a considerable gap in the protection of the national infrastructure. Trying to identify what is in fact ‘critical’ is proving to be very difficult as threats constantly evolve. An interactive prototyping tool is useful in playing out scenarios and simulating the effect of change, however existing simulators in the critical infrastructure area are typically limited in the visual representation and interactivity. To remedy this we propose the use of games technology. Through its use, critical infrastructure scenarios can be rapidly constructed, tested, and refined. In this paper, we highlight the features of games …


An Open Framework For Highly Concurrent Real-Time Hardware-In-The-Loop Simulation, Ryan C. Underwood, Bruce M. Mcmillin, Mariesa Crow Aug 2008

An Open Framework For Highly Concurrent Real-Time Hardware-In-The-Loop Simulation, Ryan C. Underwood, Bruce M. Mcmillin, Mariesa Crow

Computer Science Faculty Research & Creative Works

Hardware-in-the-loop (HIL) real-time simulation is becoming a significant tool in prototyping complex, highly available systems. The HIL approach permits testing of hardware prototypes of components that would be extremely costly or difficult to test in the deployed environment. In power system simulation, key issues are the ability to wrap the systems of equations (such as Partial Differential Equations) describing the deployed environment into real-time software models, provide low synchronization overhead between the hardware and software, and reduce reliance on proprietary platforms. This paper introduces an open source HIL simulation framework that can be ported to any standard Unix-like system on …


Analytical Characterization Of Oscillon Energy And Lifetime, Marcelo Gleiser, David Sicilia Jul 2008

Analytical Characterization Of Oscillon Energy And Lifetime, Marcelo Gleiser, David Sicilia

Dartmouth Scholarship

We develop an analytical procedure to compute all relevant physical properties of scalar field oscillons in models with quartic polynomial potentials: energy, radius, frequency, core amplitude, and lifetime. We compare our predictions to numerical simulations of models with symmetric and asymmetric double-well potentials in three spatial dimensions, obtaining excellent agreement. We also explain why oscillons have not been seen to decay in two spatial dimensions.


Using Agile Software Development Practices In A Research Oriented Distributed Simulation, Douglas James Mielke Jul 2008

Using Agile Software Development Practices In A Research Oriented Distributed Simulation, Douglas James Mielke

Computational Modeling & Simulation Engineering Theses & Dissertations

Although sometimes controversial, agile methodologies have proven to be a viable choice for some software development projects. Projects suited to agile methodologies are those that involve new technology, have requirements that change rapidly, and are controlled by small, talented teams. Much literature about agile software development leans towards business products and non-government entities. Only a handful of literature resources mention agile software development being used in government contracts and even fewer resources mention research projects. NASA's Airspace and Traffic Operations Simulation (ATOS) is a research oriented simulation that doesn't follow the traditional business project mold. In an effort to gain …


Management Of Forests Through The Application Of Advanced Technologies, Praveen Jha Dr Jun 2008

Management Of Forests Through The Application Of Advanced Technologies, Praveen Jha Dr

Praveen Jha Dr

Several state-of-art geo-spatial programs developed by the author could be applied to generate technological pathways for providing an integrated solution to the loads of problems in the forests in the most scientific, objective and effective manner so that the management prescriptions incorporating policy interventions may prove to be highly successful. Three state-of-art geo-spatial programs - Multi-Algorithm Automation Program (MAAP), Data Automatic Modification Program (DAMP) and Multi-Stage Simulation Program (MUSSIP) – developed to address the pertinent issues of conservation and sustainability could be used extensively. Based on satellite data, MAAP produces land use land cover (lulc) map of the present period, …


Large Scale Structure As A Probe Of Gravitational Slip, Scott F. Daniel, Robert R. Caldwell, Asantha Cooray, Alessandro Melchiorri May 2008

Large Scale Structure As A Probe Of Gravitational Slip, Scott F. Daniel, Robert R. Caldwell, Asantha Cooray, Alessandro Melchiorri

Dartmouth Scholarship

A new time-dependent, scale-independent parameter, ϖ, is employed in a phenomenological model of the deviation from general relativity in which the Newtonian and longitudinal gravitational potentials slip apart on cosmological scales as dark energy, assumed to be arising from a new theory of gravitation, appears to dominate the Universe. A comparison is presented between ϖ and other parametrized post-Friedmannian models in the literature. The effect of ϖ on the cosmic microwave background anisotropy spectrum, the growth of large-scale structure, the galaxy weak-lensing correlation function, and cross correlations of cosmic microwave background anisotropy with galaxy clustering are illustrated. Cosmological models with …


Modeling The Effects Of Value-Added Processing And Logistics Using Arena, Kurt A. Rosentrater, Elif Kongar Mar 2008

Modeling The Effects Of Value-Added Processing And Logistics Using Arena, Kurt A. Rosentrater, Elif Kongar

Kurt A. Rosentrater

Scarcity and cost of nonrenewable fossil fuels have been a growing focus of many energy-dependent nations, including the U.S., for the past couple of decades. There are mainly two ways to approach these problems: (1) reducing the energy dependency and/or (2) developing alternative means of energy production. Utilizing biofuels, which are renewable sources of energy, is a promising way to produce energy. But, as this industry grows, so too does the quantity of byproducts, which are known as DDGS. This paper discusses a model that has been developed to analyze the economic viability of DDGS processing, and includes both deterministic …


Simulation And Visualization Of Environments With Multidimensional Time, Luther A. Tychonievich Jan 2008

Simulation And Visualization Of Environments With Multidimensional Time, Luther A. Tychonievich

Theses and Dissertations

This work introduces the notion of computational hypertime, or the simulation and visualization of hypothetical environments possessing multidimensional time. An overview of hypertime is provided,including an intuitive visualization paradigm and a discussion of the failure of common simulation techniques when extended to include multidimensional time. A condition for differential equations describing hypertime motion to be amenable to standard time-iterative simulation techniques is provided,but is not satisfied by any known model of physics. An alternate simulation algorithm involving iterative refinement of entire equations of motion is presented,with an example implementation to solve elastic collisions in hypertime. An artificial intelligence algorithm for …


Space-Time Multiresolution Approach To Atomistic Visualization, Dipesh Bhattarai Jan 2008

Space-Time Multiresolution Approach To Atomistic Visualization, Dipesh Bhattarai

LSU Doctoral Dissertations

Time-varying three-dimensional positional atomistic data are rich in spatial and temporal information. The problem is to understand them. This work offers multiple approaches that enable such understanding. An interactive atomistic visualization system is developed integrating complex analyses with visualization to present the data on space-time multiresolution basis facilitating the information extraction and generate understanding. This work also shows the usefulness of such an integrated approach. The information obtained from the analyses represents the system at multiple length and time scales. Radial distribution function (RDF) provides a complete average spatial map of the distribution of the atoms in the system which …


Application Of Computer Simulation Modeling To Evaluate Business Continuity Plans, Jose Francisco Molina Garcia Plaza Jan 2008

Application Of Computer Simulation Modeling To Evaluate Business Continuity Plans, Jose Francisco Molina Garcia Plaza

CCE Theses and Dissertations

Business continuity plans (BCP) help organizations plan for and withstand the occurrence of unexpected events that interrupt the normal operation of business. Managers typically develop several alternate plans to minimize the business impact of unexpected events. The problem for decision makers is that comparative evaluation of BCP is typically done using subjective judgments.

This research uses a case study approach focusing on a single organization and a single business continuity application to propose the use of computer simulation as a tool for managers to identify and evaluate different BCP prior to committing resources. In the context of an insurance firm, …


Simulating Controlled Variate And Rank Correlations Based On The Power Method Transformation, Todd C. Headrick, Simon Y. Aman, T. Mark Beasley Dec 2007

Simulating Controlled Variate And Rank Correlations Based On The Power Method Transformation, Todd C. Headrick, Simon Y. Aman, T. Mark Beasley

Todd Christopher Headrick

The power method transformation is a popular algorithm used for simulating correlated non normal continuous variates because of its simplicity and ease of execution. Statistical models may consist of continuous and (or) ranked variates. In view of this, the methodology is derived for simulating controlled correlation structures between non normal (a) variates, (b) ranks, and (c) variates with ranks in the context of the power method. The correlation structure between variate-values and their associated rank-order is also derived for the power method. As such, a measure of the potential loss of information is provided when ranks are used in place …


A Middle-Ware Level Client Cache For A High Performance Computing I/O Simulator, Michael Bassily Dec 2007

A Middle-Ware Level Client Cache For A High Performance Computing I/O Simulator, Michael Bassily

All Theses

This thesis describes the design and run time analysis of the system level middle-ware cache for Hecios. Hecios is a high performance cluster I/O simulator. With Hecios, we provide a simulation environment that accurately captures the performance characteristics of all the components in a clusterwide parallel file system. Hecios was specifically modeled after PVFS2. It was designed to be extensible and to easily allow for various component modules to be easily replaced by those that model other system types. Built around the OMNeT++ simulation package, Hecios' inner-cluster communication module is easily adaptable to any TCP/IP based protocol and all standard …


A Contextualized Web-Based Learning Environments For Devs Models, Inthira Srivrunyoo Nov 2007

A Contextualized Web-Based Learning Environments For Devs Models, Inthira Srivrunyoo

Computer Science Theses

With the advance in applying technology in education, the traditional lecture-driven teaching style is gradually replaced by a more active teaching style where the students play a more active rule in the learning process. In this paper we introduce a new initiative to provide a suite of online tools for learning DEVS model. The uniqueness of this tutorial project is the integration of information technology and multimedia into education through the development of an interactive tutorial and the characteristic of contextualized learning. The tutorial teaches students about the basic aspects of discrete event system and simulation. The interactive tutorial fully …


Evaluating Opportunistic Routing Protocols With Large Realistic Contact Traces, Libo Song, David Kotz Sep 2007

Evaluating Opportunistic Routing Protocols With Large Realistic Contact Traces, Libo Song, David Kotz

Dartmouth Scholarship

Traditional mobile ad hoc network (MANET) routing protocols assume that contemporaneous end-to-end communication paths exist between data senders and receivers. In some mobile ad hoc networks with a sparse node population, an end-to-end communication path may break frequently or may not exist at any time. Many routing protocols have been proposed in the literature to address the problem, but few were evaluated in a realistic “opportunistic” network setting. We use simulation and contact traces (derived from logs in a production network) to evaluate and compare five existing protocols: direct-delivery, epidemic, random, PRoPHET, and Link-State, as well as our own proposed …


Bioanalyze: A Tool For The Simulation And Analysis Of Biological Systems, James Norman Aug 2007

Bioanalyze: A Tool For The Simulation And Analysis Of Biological Systems, James Norman

All Theses

Scientists have turned to a more systemic approach to biology in order to fully understand the complex functionality of living organisms. Biologist and Geneticist have compiled an impressive amount of experimental data for a multitude of biological systems. Modeling and simulation of these systems has become a prominent tool in the field of Systems Biology. In this paper we present a review of General Systems Theory, Systems Biology, and introduce BioAnalyze. BioAnalyze is a web application designed to simulate, and analyze, the functional dynamics of biological systems.


An Adaptive Bayesian Approach To Bernoulli-Response Clinical Trials, Andrew W. Stacey Aug 2007

An Adaptive Bayesian Approach To Bernoulli-Response Clinical Trials, Andrew W. Stacey

Theses and Dissertations

Traditional clinical trials have been inefficient in their methods of dose finding and dose allocation. In this paper a four-parameter logistic equation is used to model the outcome of Bernoulli-response clinical trials. A Bayesian adaptive design is used to fit the logistic equation to the dose-response curve of Phase II and Phase III clinical trials. Because of inherent restrictions in the logistic model, symmetric candidate densities cannot be used, thereby creating asymmetric jumping rules inside the Markov chain Monte Carlo algorithm. An order restricted Metropolis-Hastings algorithm is implemented to account for these limitations. Modeling clinical trials in a Bayesian framework …


A Hybrid Of Plot-Based And Character-Based Interactive Storytelling, Yundong Cai, Chunyan Miao, Ah-Hwee Tan, Zhiqi Shen Jun 2007

A Hybrid Of Plot-Based And Character-Based Interactive Storytelling, Yundong Cai, Chunyan Miao, Ah-Hwee Tan, Zhiqi Shen

Research Collection School Of Computing and Information Systems

Interactive storytelling in the virtual environment attracts a lot of research interests in recent years. Story plot and character are two most important elements of a story. Based on these two elements, currently there are two research directions: plot-based and character-based interactive storytelling. However, plot-based approach lacks the refinement of character behaviors as character-based approach. On the other side, character-based approach does not follow a well organized story plot so that the moral of the story might be distorted. Therefore, there is a need to develop an integrated framework to achieve the balance between conveying story moral and enhancing the …


Adaptive Treatment Of Van Der Waals Interactions In Empirical Bond-Order Potentials With Application To Junction Formation In Carbon Nanotubes, Aibing Liu May 2007

Adaptive Treatment Of Van Der Waals Interactions In Empirical Bond-Order Potentials With Application To Junction Formation In Carbon Nanotubes, Aibing Liu

All Dissertations

Molecular dynamics (MD) simulation of reactive condensed-phase hydrocarbon systems is a challenging research area. The AIREBO potential is particularly useful in this area because it can simulate bond breaking and bond forming during chemical reactions. It also includes non-bonded interactions for systems with significant intermolecular interactions.

The first part of this dissertation describes a method to adaptively incorporate van der Waals interaction of carbon atoms into the AIREBO force field. In bond-order potentials, the covalent bonding interactions adapt to the local chemical environment, allowing bonded interactions to change in response to local chemical changes.
Non-bonded interactions should adjust to their …