Physical Sciences and Mathematics Commons^™

Time Varying Parameter Estimation Scheme For A Linear Stochastic Differential Equation, Olusegun Michael Otunuga

Olusegun Michael Otunuga

In this work, an attempt is made to estimate time varying parameters in a linear stochastic differential equation. By defining mk as the local admissible sample/data observation size at time tk, parameters and state at time tk are estimated using past data on interval [tk−mk+1, tk]. We show that the parameter estimates at each time tk converge in probability to the true value of the parameters being estimated. A numerical simulation is presented by applying the local lagged adapted generalized method of moments (LLGMM) method to the stochastic differential models governing prices of energy …

The Open World Microorganism, Stephen Thompson

Stephen Thompson

Simulating Magnetospheres With Numerical Relativity: The Giraffe Code, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

Numerical Relativity is successful in the simulation of black holes and gravitational waves. In recent years, teams have tackled the problem of the interaction of gravitational and electromagnetic waves. We developed a new code for the numerical simulation of neutron and black hole magnetospheres, using the FFE formalism. We tested the performance of the new code named GiRaFFE, in 1D and 3D test suits. We will study magnetospheres, focusing on jets by the Blandford -Znajek mechanism.

On The Simulation And Mitigation Of Anisoplanatic Optical Turbulence For Long Range Imaging, Russell C. Hardie, Daniel A. Lemaster

Russell C. Hardie

We describe a numerical wave propagation method for simulating long range imaging of an extended scene under anisoplanatic conditions. Our approach computes an array of point spread functions (PSFs) for a 2D grid on the object plane. The PSFs are then used in a spatially varying weighted sum operation, with an ideal image, to produce a simulated image with realistic optical turbulence degradation. To validate the simulation we compare simulated outputs with the theoretical anisoplanatic tilt correlation and differential tilt variance. This is in addition to comparing the long- and short-exposure PSFs, and isoplanatic angle. Our validation analysis shows an …

Simulation Of Anisoplanatic Imaging Through Optical Turbulence Using Numerical Wave Propagation With New Validation Analysis, Russell C. Hardie, Jonathan D. Power, Daniel A. Lemaster, Douglas R. Droege, Szymon Gladysz, Santasri Bose-Pillai

Russell C. Hardie

We present a numerical wave propagation method for simulating imaging of an extended scene under anisoplanatic conditions. While isoplanatic simulation is relatively common, few tools are specifically designed for simulating the imaging of extended scenes under anisoplanatic conditions. We provide a complete description of the proposed simulation tool, including the wave propagation method used. Our approach computes an array of point spread functions (PSFs) for a two-dimensional grid on the object plane. The PSFs are then used in a spatially varying weighted sum operation, with an ideal image, to produce a simulated image with realistic optical turbulence degradation. The degradation …

Patient-Centered Appointment Scheduling Using Agent-Based Simulation, Tammy Toscos, Ayten Turkcan, Brad Doebbeling

Tammy R Toscos

Enhanced access and continuity are key components of patient-centered care. Existing studies show that several interventions such as providing same day appointments, walk-in services, after-hours care, and group appointments, have been used to redesign the healthcare systems for improved access to primary care. However, an intervention focusing on a single component of care delivery (i.e. improving access to acute care) might have a negative impact other components of the system (i.e. reduced continuity of care for chronic patients). Therefore, primary care clinics should consider implementing multiple interventions tailored for their patient population needs. We collected rapid ethnography and observations to …

Assessing The Probability That A Finding Is Genuine For Large-Scale Genetic Association Studies, Chia-Ling Kuo, Olga A. Vsevolozhskaya, Dmitri V. Zaykin

Olga A. Vsevolozhskaya

Genetic association studies routinely involve massive numbers of statistical tests accompanied by P-values. Whole genome sequencing technologies increased the potential number of tested variants to tens of millions. The more tests are performed, the smaller P-value is required to be deemed significant. However, a small P-value is not equivalent to small chances of a spurious finding and significance thresholds may fail to serve as efficient filters against false results. While the Bayesian approach can provide a direct assessment of the probability that a finding is spurious, its adoption in association studies has been slow, due in part to the ubiquity …

Cepsim: A Simulator For Cloud-Based Complex Event Processing, Wilson Higashino, Miriam Capretz, Luiz Bittencourt

Wilson A Higashino

As one of the Vs defining Big Data, data velocity brings many new challenges to traditional data processing approaches. The adoption of cloud environments in complex event processing (CEP) systems is a recent architectural style that aims to overcome these challenges. Validating cloud-based CEP systems at the required Big Data scale, however, is often a laborious, error-prone, and expensive task. This article presents CEPSim, a new simulator that has been developed to facilitate this validation process. CEPSim extends CloudSim, an existing cloud simulator, with an application model based on directed acyclic graphs that is used to represent continuous CEP queries. …

Functional Analysis Of Variance For Association Studies, Olga A. Vsevolozhskaya, Dmitri V. Zaykin, Mark C. Greenwood, Changshuai Wei, Qing Lu

Olga A. Vsevolozhskaya

While progress has been made in identifying common genetic variants associated with human diseases, for most of common complex diseases, the identified genetic variants only account for a small proportion of heritability. Challenges remain in finding additional unknown genetic variants predisposing to complex diseases. With the advance in next-generation sequencing technologies, sequencing studies have become commonplace in genetic research. The ongoing exome-sequencing and whole-genome-sequencing studies generate a massive amount of sequencing variants and allow researchers to comprehensively investigate their role in human diseases. The discovery of new disease-associated variants can be enhanced by utilizing powerful and computationally efficient statistical methods. …

Collective Librations Of Water Molecules In The Crystal Lattice Of Rubidium Bromide: Experiment And Simulation, L M. Lepodise, J Horvat, Roger A. Lewis

Josip Horvat

Terahertz spectroscopy of RbBr reveals four prominent absorption lines at room temperature and a further 15 lines at 10 K. Via density-functional-theory (DFT) numerical modelling using the PBE0 hybrid GGA functional, all the absorptions are identified as correlated librations of water molecules in the RbBr lattice. Each libration mode is a combination of rocking, wagging and twisting motions of the water molecules. The number of libration lines and numerical modelling show that the C2v symmetry of water in RbBr is broken. Our modelling shows that the distribution of libration amplitudes and phases for different water molecules in the RbBr unit …

Numerical Simulation Of Diffusion Mri Signals Using An Adaptive Time-Stepping Method, Jing-Rebecca Li, Donna Calhoun, Cyril Poupon, Denis Le Bihan

Donna Calhoun

The effect on the MRI signal of water diffusion in biological tissues in the presence of applied magnetic field gradient pulses can be modelled by a multiple compartment Bloch–Torrey partial differential equation. We present a method for the numerical solution of this equation by coupling a standard Cartesian spatial discretization with an adaptive time discretization. The time discretization is done using the explicit Runge–Kutta–Chebyshev method, which is more efficient than the forward Euler time discretization for diffusive- type problems. We use this approach to simulate the diffusion MRI signal from the extra-cylindrical compartment in a tissue model of the brain …

Simulating Univariate And Multivariate Tukey G-And-H Distributions Based On The Method Of Percentiles, Tzu-Chun Kou, Todd C. Headrick

Todd Christopher Headrick

This paper derives closed-form solutions for the 𝑔-and-ℎ shape parameters associated with the Tukey family of distributions based on the method of percentiles (MOP). A proposed MOP univariate procedure is described and compared with the method of moments (MOM) in the context of distribution fitting and estimating skew and kurtosis functions. The MOP methodology is also extended from univariate to multivariate data generation. A procedure is described for simulating nonnormal distributions with specified Spearman correlations. The MOP procedure has an advantage over the MOM because it does not require numerical integration to compute intermediate correlations. Simulation results demonstrate that the …

Nanohub - Crystal Viewer 2.0, Kevin Margatan, Gerhard Klimeck

Gerhard Klimeck

nanoHUB is an online compilation of tools for simulations. Equipped with 3-D simulations and a capability to solve very complex calculations, nanoHUB provides its users worldwide with various tools to help them finish their assignments. One of the tools available is called a Crystal Viewer Tool, an advanced crystal visualization tool. This tool allows users to generate various crystal types including their every single detail. Currently, a newer version, called Crystal Viewer 2.0, is being tested prior to its release. However, this tool is lacking some important features and a GUI that is not as user friendly as expected. The …

Next Generation Crystal Viewing Tool, Zach Schaffter, Gerhard Klimeck

Gerhard Klimeck

The science and engineering community is limited when it comes to crystal viewing software tools. Each tool lacks in a different area such as customization of structures or visual output. Crystal Viewer 2.0 was created to have all of these features in one program. This one tool simulates virtually any crystal structure with any possible material. The vtkvis widget offers users advanced visual options not seen in any other crystal viewing software. In addition, the powerful engine behind Crystal Viewer 2.0, nanoelectronic modeling 5 or (NEMO5), performs intensive atomic calculations depending on user input. A graphical user interface, or GUI, …

Distance Of Closest Approach Of Two Arbitrary Hard Ellipses In Two Dimensions, Xiaoyu Zheng, Peter Palffy-Muhoray

Peter Palffy-Muhoray

The distance of closest approach of hard particles is a key parameter of their interaction and plays an important role in the resulting phase behavior. For nonspherical particles, the distance of closest approach depends on orientation, and its calculation is surprisingly difficult. Although overlap criteria have been developed for use in computer simulations [ Vieillard-Baron J. Chem. Phys. 56 4729 (1972); Perram and Wertheim J. Comput. Phys. 58 409 (1985)], no analytic solutions have been obtained for the distance of closest approach of ellipsoids in three dimensions, or, until now, for ellipses in two dimensions. We have derived an analytic …

Model For The Director And Electric Field In Liquid Crystal Cells Having Twist Walls Or Disclination Lines, G. Panasyuk, David W. Allender

David W Allender

Two examples of the director structure and electric field in patterned electrode liquid crystal cells are studied using a recently developed calculational model. First, a display cell that exhibits a homeotropic to multidomainlike transition with twist wall structures has been considered for a liquid crystal with positive dielectric anisotropy. The model elucidates the behavior of the electric field. Calculations show good agreement between the model and direct computer solution of the Euler-Lagrange equations, but the model is at least 30 times faster. Second, the possibility that a cell has +/-1/2 disclination lines instead of a wall defect is probed. A …

Simulation Of Circuit Creation In Tor: Preliminary Results, William Boyd, Norman Danner, Danny Krizanc

Norman Danner

We describe a methodology for simulating Tor relay up/down behavior over time and give some preliminary results.

The Evolution Of Modular Product Architectures And The Emergence Of Platform Ecosystems, C. Jason Woodard, Eric K. Clemons

C. Jason Woodard

No abstract provided.

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

Dr Ian Piper

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 …

Human Motion Simulation And Action Corpus, Gang Zheng, Wanqing Li, Philip Ogunbona, Liju Dong, Igor Kharitonenko

Associate Professor Wanqing Li

Acquisition of large scale good quality training samples is becoming a major issue in machine learning based human motion analysis. This paper presents a method to simulate continuous gross human body motion with the intention to establish a human motion corpus for learning and recognition. The simulation is achieved by a temporal-spatialtemporal decomposition of human motion into actions, joint actions and actionlets based on the human kinematic model. The actionlet models the primitive moving phase of a joint and represents the muscle movement governed by kinesiological principles. Joint actions and body actions are constructed from actionlets through constrained concatenation and …

Simulation Of Human Motion For Learning And Recognition, Gang Zheng, Wanqing Li, Philip Ogunbona, Liju Dong, Igor Kharitonenko

Associate Professor Wanqing Li

Acquisition of good quality training samples is becoming a major issue in machine learning based human motion analysis. This paper presents a method to simulate human body motion with the intention to establish a human motion corpus for learning and recognition. The simulation is achieved by a unique temporal-spatial-temporal decomposition of human body motion into actions, joint actions and actionlets based on the human kinematic model. The actionlet models the primitive moving phase of a joint and can be simulated based on the kinesiological study. A joint action is formed by proper concatenation of actionlets and an action is a …

Human Motion Simulation And Action Corpus, Gang Zheng, Wanqing Li, Philip Ogunbona, Liju Dong, Igor Kharitonenko

Dr Igor Kharitonenko

Acquisition of large scale good quality training samples is becoming a major issue in machine learning based human motion analysis. This paper presents a method to simulate continuous gross human body motion with the intention to establish a human motion corpus for learning and recognition. The simulation is achieved by a temporal-spatialtemporal decomposition of human motion into actions, joint actions and actionlets based on the human kinematic model. The actionlet models the primitive moving phase of a joint and represents the muscle movement governed by kinesiological principles. Joint actions and body actions are constructed from actionlets through constrained concatenation and …

Modelling And Simulation Of An Adaptive Neuro-Fuzzy Inference System (Anfis) For Mobile Learning, Ahmed Al-Hmouz, Jun Shen, Rami Al-Hmouz, Jun Yan

Dr Jun Yan

With recent advances in mobile learning (m-learning), it is becoming possible for learning activities to occur everywhere. The learner model presented in our earlier work was partitioned into smaller elements in the form of learner profiles, which collectively represent the entire learning process. This paper presents an Adaptive Neuro-Fuzzy Inference System (ANFIS) for delivering adapted learning content to mobile learners. The ANFIS model was designed using trial and error based on various experiments. This study was conducted to illustrate that ANFIS is effective with hybrid learning, for the adaptation of learning content according to learners' needs. Study results show that …

Design And Simulation Of A Ds-Th-Uwb System Using Simulink/Matlab For First Arriving Rays In A Non Line Of Sight Wireless Scenario, Peter Vial

Dr Peter Vial

An Ultra Wideband system was developed using Simulink in previous work. Using this developed model for Ultra Wideband (UWB) Pulse Position Modulation (PPM) within Simulink, we apply Direct Sequence Walsh codes across Time Hopping Patterns to smooth out the spectral characteristics with Pulse Position Modulation. A non-line of sight Saleh-Valenzuela (SV) model is used to characterize the wireless channel. The system is described and results are presented for the scenario where the first arriving rays are used to detect the transmitted message. For this non-optimum technique (in that for non line of sight the strongest signal rays are available after …

Modelling And Simulation Of An Adaptive Neuro-Fuzzy Inference System (Anfis) For Mobile Learning, Ahmed Al-Hmouz, Jun Shen, Rami Al-Hmouz, Jun Yan

Dr Jun Shen

With recent advances in mobile learning (m-learning), it is becoming possible for learning activities to occur everywhere. The learner model presented in our earlier work was partitioned into smaller elements in the form of learner profiles, which collectively represent the entire learning process. This paper presents an Adaptive Neuro-Fuzzy Inference System (ANFIS) for delivering adapted learning content to mobile learners. The ANFIS model was designed using trial and error based on various experiments. This study was conducted to illustrate that ANFIS is effective with hybrid learning, for the adaptation of learning content according to learners' needs. Study results show that …

Simamph: An Agent-Based Simulation Model For Exploring The Use Of Psychostimulants And Related Harm Amongst Young Australians, Pascal Perez, Anne Dray, David Moore, Paul Dietze, Gabriele Bammer, Rebecca Jenkinson, Christine Siokou, Rachael Green, Susan Hudson, Lisa Maher

Professor Pascal Perez

Background: Computer simulations provide a useful tool for bringing together diverse sources of information in order to increase understanding of the complex aetiology of drug use and related harm, and to inform the development of effective policies. In this paper, we describe SimAmph, an agent-based simulation model for exploring how individual perceptions, peer influences and subcultural settings shape the use of psychostimulants and related harm amongst young Australians. Methods: We present the conceptual architecture underpinning SimAmph, the assumptions we made in building it, the outcomes of sensitivity analysis of key model parameters and the results obtained when we modelled a …

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

Professor Pascal Perez

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 …

Are Drug Detection Dogs And Mass-Media Campaigns Likely To Be Effective Policy Responses To Psychostimulant Use And Related Harm? Results From An Agent-Based Simulation Model, David Moore, Lisa Maher, Christine Siokou, Rachael Green, Anne Dray, Rebecca Jenkinson, Susan Hudson, Gabriele Bammer, Pascal Perez, Paul Dietze

Professor Pascal Perez

Background Agent-based simulation models can be used to explore the impact of policy and practice on drug use and related consequences. In a linked paper (Perez et al., 2011), we described SimAmph, an agent-based simulation model for exploring the use of psychostimulants and related harm amongst young Australians. Methods In this paper, we use the model to simulate the impact of two policy scenarios on engagement in drug use and experience of drug-related harm: (i) the use of passive-alert detection (PAD) dogs by police at public venues and (ii) the introduction of a mass-media drug prevention campaign. Results The findings …

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

Associate Professor Kwan-Wu Chin

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.

Human Motion Simulation And Action Corpus, Gang Zheng, Wanqing Li, Philip Ogunbona, Liju Dong, Igor Kharitonenko

Professor Philip Ogunbona

Acquisition of large scale good quality training samples is becoming a major issue in machine learning based human motion analysis. This paper presents a method to simulate continuous gross human body motion with the intention to establish a human motion corpus for learning and recognition. The simulation is achieved by a temporal-spatialtemporal decomposition of human motion into actions, joint actions and actionlets based on the human kinematic model. The actionlet models the primitive moving phase of a joint and represents the muscle movement governed by kinesiological principles. Joint actions and body actions are constructed from actionlets through constrained concatenation and …