Physical Sciences and Mathematics Commons^™

Force/Position Hybrid Control Method For Surface Parts Polishing Robot, Yufeng Ding, Xinpu Min

Journal of System Simulation

Abstract: A force/position hybrid control method for polishing the complex surface with an industrial robot is put forward. The method can achieve the stable force control and precise position control to ensure the consistency of the material removal rate at different normal vectors. After the trajectory of the normal vector is planned in CAD software, the force signal feedback from the sensor and the PI controller in the normal vector direction are combined,and the robot end tool corrects the motion trajectory in the vector direction of the surface to indirectly control the contact force between the tool and the surface. …

Simulating Quantum Systems Using The D-Wave Quantum Computer, Justin M. Copenhaver, Raunaq Kumaran, Birgit Kaufmann, Adam Wasserman

Discovery Undergraduate Interdisciplinary Research Internship

No abstract provided.

Can Auxiliary Information Improve Rasch Estimation At Small Sample Sizes?, Derek Sauder

Dissertations, 2020-current

The Rasch model is commonly used to calibrate multiple choice items. However, the sample sizes needed to estimate the Rasch model can be difficult to attain (e.g., consider a small testing company trying to pretest new items). With small sample sizes, auxiliary information besides the item responses may improve estimation of the item parameters. The purpose of this study was to determine if incorporating item property information (i.e., characteristics of the items related to item difficulty) in a random effects linear logistic test model (RE-LLTM) would improve estimation of item difficulty. A simulation study was conducted that varied sample size, …

Propensity Score Matching And Generalized Boosted Modeling In The Context Of Model Misspecification: A Simulation Study, Briana G. Craig

Masters Theses, 2020-current

In the absence of random assignment, researchers must consider the impact of selection bias – pre-existing covariate differences between groups due to differences among those entering into treatment and those otherwise unable to participate. Propensity score matching (PSM) and generalized boosted modeling (GBM) are two quasi-experimental pre-processing methods that strive to reduce the impact of selection bias before analyzing a treatment effect. PSM and GBM both examine a treatment and comparison group and either match or weight members of those groups to create new, balanced groups. The new, balanced groups theoretically can then be used as a proxy for the …

Investigating The Stability Of Observed Low Semi-Major Axis Exoplanetary Systems With Hypothetical Outer Planets Using The Program Mercury6, Kendall Butler

Honors College

This project investigates the stability of observed planetary systems, and whether this stability remains in the presence of additional outer planets. This made use of the program Mercury6, an n-body integrator that computes the changes in planetary orbits over time. The Systems HD 136352, GJ 9827, and HD 7924 were studied with initial conditions taken from the available observational data. This information was curated using the online NASA Exoplanet archive of confirmed exoplanets. With these initial conditions, Mercury6 computed the changing planetary orbits of each system for 5 million years. For each of these systems, a single outer planet, which …

Uav 6dof Simulation And Kalman Filter For Localizing Radioactive Sources, John G. Goulet

Electronic Theses and Dissertations

Unmanned Aerial Vehicles (UAVs) expand the available mission-space for a wide range of budgets. Using MATLAB, this project has developed a six degree of freedom (6DOF) simulation of UAV flight, an Extended Kalman Filter (EKF), and an algorithm for localizing radioactive sources using low-cost hardware. The EKF uses simulated low-cost instruments in an effort to estimate the UAV state throughout simulated flight.

The 6DOF simulates aerodynamics, physics, and controls throughout the flight and provides outputs for each time step. Additionally, the 6DOF simulation offers the ability to control UAV flight via preset waypoints or in realtime via keyboard input.

Using …

A Model For The Spread Of Infectious Diseases In A Region, Elizabeth Hunter, Brian Mac Namee, John D. Kelleher

Articles

In understanding the dynamics of the spread of an infectious disease, it is important to understand how a town’s place in a network of towns within a region will impact how the disease spreads to that town and from that town. In this article, we take a model for the spread of an infectious disease in a single town and scale it up to simulate a region containing multiple towns. The model is validated by looking at how adding additional towns and commuters influences the outbreak in a single town. We then look at how the centrality of a town …

One Design Mode Of Highly Configurable Modular Simulation System, Chunsheng Hu, Chengdong Xu, Penfei Zhang

Journal of System Simulation

Abstract: The computer simulation technology is an essential verification way to the design, construction and application optimization of the modern complex system. Following the continuous growing complexity of the system, the higher requirement on the configurability of the simulation system is needed to face the rapidly change. Based on the analysis on the configurability and some coupling factors with the adverse effect, a design mode of highly configurable and open and easy to expend modular simulation system is proposed. The results show that, despite the cost of some real-time performance, the design mode can realize the high configurability of the …

Dot: Gene-Set Analysis By Combining Decorrelated Association Statistics, Olga A. Vsevolozhskaya, Min Shi, Fengjiao Hu, Dmitri V. Zaykin

Biostatistics Faculty Publications

Historically, the majority of statistical association methods have been designed assuming availability of SNP-level information. However, modern genetic and sequencing data present new challenges to access and sharing of genotype-phenotype datasets, including cost of management, difficulties in consolidation of records across research groups, etc. These issues make methods based on SNP-level summary statistics particularly appealing. The most common form of combining statistics is a sum of SNP-level squared scores, possibly weighted, as in burden tests for rare variants. The overall significance of the resulting statistic is evaluated using its distribution under the null hypothesis. Here, we demonstrate that this basic …

Economic Review Of Pasture Development Options For North Australian Beef Enterprises, Neil D. Macleod, Dianne Mayberry, Lindsay Bell, Ian Watson

IGC Proceedings (1993-2023)

Beef cattle grazing (~14 million head) native pastures is the dominant economic use of northern grazing lands (2.3 million km2). Few enterprises make positive economic returns in most years or achieve the necessary productivity gains (~2% per annum) to offset an ongoing cost-price squeeze (McCosker et al., 2010). A significant contributor to poor performance is low reproductive performance, management of first calving heifers, calf growth and weaning rates and liveweight gain - linked to nutrition and the low quality of pastures. Pasture development technologies (Gramshaw and Walker, 1988) are available but uptake has been poor. Three pasture development options …

Improved Modelling Of Lucerne (Medicago Sativa L.) Production For Grazing Livestock, Andrew Smith

IGC Proceedings (1993-2023)

Lucerne (or alfalfa; Medicago sativa L.)-based pastures play an important role in livestock and mixed farms (croplivestock) in Australia. If lucerne is to be more widely adopted, it will be important that landholders are able to plan to maximize its benefits to their livestock enterprises (usually as a part of a diverse feed base), as well as assess the benefits and minimizing the costs of lucerne phases to subsequent crops. However, the ability to accurately model lucerne plant physiology across the full spectrum of environments, genotypes and cultivars remains elusive. This study aimed to review and revise the description of …

Emergency Evacuation Simulation For Dense Passenger Flow In A Rail Transit Transfer Station, Xu Hui, Tian Cheng, Wang Yong

Journal of System Simulation

Abstract: The rail transit is one of the important modes of the public transportation, and its safety operation is crucial. Based on the passenger volume and structure features that have been obtained through the field investigation in Chongqing Lianglukou railway station in China, a multi-level rail transit transfer station simulation model is built to analyze the evacuation process of pedestrians in the consideration of explosion and other emergencies by the software AnyLogic. The evacuation routes and evacuation time of passengers during emergency evacuation in a rail transit transfer station are studied. The research aims at verifying the emergency evacuation capacity …

Simulation Analysis On Flexible Track Drilling Machine Based On Adams, Yanchao Zhang, Ting Wang, Danlong Song

Journal of System Simulation

Abstract: The three-dimensional model of the flexible track drilling machine is designed by the virtual prototyping technology. The model is imported into ADAMS (Automatic Dynamic Analysis of Mechanical Systems) software to carry out the kinematics and dynamic simulation analysis of its virtual prototype, and the rationality and feasibility of the system design are evaluated. Through the comparative analysis, the reasonable driving velocity and acceleration parameters of the hole making system are given. According to the analysis of the dynamic characteristics of the systems, the asymmetric driving problems in the system are found and the corresponding improvement scheme is put forward. …

Estimating Error And Bias In Offline Evaluation Results, Mucun Tian, Michael D. Ekstrand

Computer Science Faculty Publications and Presentations

Offline evaluations of recommender systems attempt to estimate users’ satisfaction with recommendations using static data from prior user interactions. These evaluations provide researchers and developers with first approximations of the likely performance of a new system and help weed out bad ideas before presenting them to users. However, offline evaluation cannot accurately assess novel, relevant recommendations, because the most novel items were previously unknown to the user, so they are missing from the historical data and cannot be judged as relevant.

We present a simulation study to estimate the error that such missing data causes in commonly-used evaluation metrics in …

Design Of Air Defense Missile Weapon System Simulation Platform Based On Xsim Platform, Kaizhi Ruan, Qingqing Yuan, Wenhua Zhai, Zhiqiang Zhang

Journal of System Simulation

Abstract: Taking the system simulation technology which applied to the scheme argumentation, optimization design, flight test forecast, battle effectiveness evaluation of air defense missile weapon system as background, the design method of air defense missile weapon system simulation platform based on Xsim platform was put forward. The total configuration design, model design and simulation process design of the platform were discussed. An simulation platform of an air defense missile weapon system was accomplished. The result proves the platform can simulate the battle process of air defense missile weapon system, support the simulation work of air defense weapon at different …

Modelling Complex Sheep Systems Using Ausfarm, Susan M. Robertson, Michael A. Friend

IGC Proceedings (1993-2023)

Simulation modelling can be a valuable method for extrapolating experimental findings to different weather or management conditions. However, most of the decision support tools which are available for sheep grazing systems, for example GrassGro® (Donnelly et al. 1997), are limited to modelling of relatively simple sheep management. This makes validation of simulations against experimental results difficult where management changes from year to year, and where more complex sheep management is used. This study evaluated the use of the AusFarm® decision support tool (Moore et al. 2007) to model a split-joined sheep system, using different ram breeds against experimental …

Towards Agent-Based Traffic Simulation Using Live Data From Sensors For Smart Cities, Johan Barthelemy, Yan Qian, Pascal Perez

SMART Infrastructure Facility - Papers

The Smart City and Internet-of-Things revolutions enable the collection of various types of data in real-time through sensors. This data can be used to improve the decision tools and simulations used by city planners. This paper presents a new framework for real-time traffic simulation integrating an agent-based methodology with live CCTV and other sensor data while respecting the privacy regulations. The framework simulates traffic flows of pedestrians, vehicles and bicycles and their interactions. The approach has been applied in Liverpool (NSW, Australia) showing promising preliminary results and can easily ingest additional sensor data, e.g. air quality.

Signal Passing Self-Assembly Simulates Tile Automata, Angel A. Cantu, Austin Luchsinger, Robert Schweller, Tim Wylie

Computer Science Faculty Publications and Presentations

The natural process of self-assembly has been studied through various abstract models due to the abundant applications that benefit from self-assembly. Many of these different models emerged in an effort to capture and understand the fundamental properties of different physical systems and the mechanisms by which assembly may occur. A newly proposed model, known as Tile Automata, offers an abstract toolkit to analyze and compare the algorithmic properties of different self-assembly systems. In this paper, we show that for every Tile Automata system, there exists a Signal-passing Tile Assembly system that can simulate it. Finally, we connect our result with …

Planar Motion Control Of A Cube Satellite Using Cold Gas Thrusters, Christian Lozoya

Open Access Theses & Dissertations

This Thesis presents a mathematical model developed for the computational simulation ofCubeSat movement using four thrusters that permit uniaxial translation and rotation. Arbitrary functions are fit to boundary conditions to simulate the force, acceleration, velocity, and displacement of the CubeSat along a plane. The model is used to derive a motion control algorithm assuming constant pressure and mass. A single model describes both translation and rotation. This Thesis also explores the relationship between propellant consumption and the time required to complete a displacement implied by the model.

One-Dimensional Kinetic Particle-In-Cell Simulations Of Various Plasma Distributions, Richard N. Vanderburgh

Browse all Theses and Dissertations

A one-dimensional kinetic particle-in-cell (PIC) MATLAB simulation was created to demonstrate the time-evolution of various plasma distributions. Building on previous plasma PIC programs written in FORTRAN and Python, this work recreates the computational and diagnostic tools of these packages in a more user- and educational-friendly development environment. Plasma quantities such as plasma frequency and species charge-mass ratios are arbitrarily defined. A one-dimensional spatial environment is defined by total length and number and size of spatial grid points. In the first time-step, charged particles are given initial positions and velocities on a spatial grid. After initialization, the program solves for the …

Geoaware - A Simulation-Based Framework For Synthetic Trajectory Generation From Mobility Patterns, Jameson D. Morgan

Browse all Theses and Dissertations

Recent advances in location acquisition services have resulted in vast amounts of trajectory data; providing valuable insight into human mobility. The field of trajectory data mining has exploded as a result, with literature detailing algorithms for (pre)processing, map matching, pattern mining, and the like. Unfortunately, obtaining trajectory data for the design and evaluation of such algorithms is problematic due to privacy, ethical, dataset size, researcher access, and sampling frequency concerns. Synthetic trajectories provide a solution to such a problem as they are cheap to produce and are derived from a fully controllable generation procedure. Citing deficiencies in modern synthetic trajectory …

Assessing Robustness Of The Rasch Mixture Model To Detect Differential Item Functioning - A Monte Carlo Simulation Study, Jinjin Huang

Electronic Theses and Dissertations

Measurement invariance is crucial for an effective and valid measure of a construct. Invariance holds when the latent trait varies consistently across subgroups; in other words, the mean differences among subgroups are only due to true latent ability differences. Differential item functioning (DIF) occurs when measurement invariance is violated. There are two kinds of traditional tools for DIF detection: non-parametric methods and parametric methods. Mantel Haenszel (MH), SIBTEST, and standardization are examples of non-parametric DIF detection methods. The majority of parametric DIF detection methods are item response theory (IRT) based. Both non-parametric methods and parametric methods compare differences among subgroups …

Automatic Gaze Classification For Aviators: Using Multi-Task Convolutional Networks As A Proxy For Flight Instructor Observation, Justin Wilson, Sandro Scielzo, Sukumaran Nair, Eric C. Larson

International Journal of Aviation, Aeronautics, and Aerospace

In this work, we investigate how flight instructors observe aviator scan patterns and assign quality to an aviator's gaze. We first establish the reliability of instructors to assign similar quality to an aviator's scan patterns, and then investigate methods to automate this quality using machine learning. In particular, we focus on the classification of gaze for aviators in a mixed-reality flight simulation. We create and evaluate two machine learning models for classifying gaze quality of aviators: a task-agnostic model and a multi-task model. Both models use deep convolutional neural networks to classify the quality of pilot gaze patterns for 40 …

An Efficient Reliability Simulation Tool For Lifetime-Aware Analog Circuit Synthesis, Engi̇n Afacan

Turkish Journal of Electrical Engineering and Computer Sciences

Time-dependent degradation (aging) has become more severe in modern CMOS technologies. Therefore, it is highly critical to capture the variation effects and design reliable circuits against aging. Simulation of time-dependent variations is quite complicated since the degradation is a function of time, where the step count of simulation directly affects the accuracy and the efficiency of the analysis. Commercial simulator tools use a constant step count during reliability simulations, in which choosing a large step count degrades the efficiency whereas keeping it small may result in accuracy problems. To overcome this bottleneck, a couple of different approaches have been proposed …

Research On Simulation Optimization Of Disk-Based Storage Operation Mode In Warehouse, Danlan Xie, Liu Meng, Haihong Yu, Chen Jing, Yubo Zhou, Kazi Mohiuddin

Journal of System Simulation

Abstract: As the efficiency of operation affects the overall competitiveness of the port, it is very necessary to design the storage operation mode reasonably. A disk-based storage operation mode is proposed. And the simulation model is established by using the logistics simulation software FlexSim based on the operational requirements of the warehouse. Through a large number of simulation experiments, comparing the primary storage mode with the disk-based storage mode, the results of the increase in total idle rate and the more balanced distribution of each hour utilization ratio of the forklifts are obtained. The result verifies the feasibility and effectiveness …

Research On Simulation Platform For Equipment System Analysis, Yuping Li, Shaojie Mao, Zhenqi Ju, Zhou Fang, Guoqiang Yan

Journal of System Simulation

Abstract: With the development of equipment construction from platform-centric to network-centric, simulation analysis of equipment system is an important means and tool to support the transformation and development of equipment construction under the condition of multi-task joint operation. Starting from the requirement of system simulation analysis, a cloud-based equipment system simulation architecture is proposed to realize flexible and configurable simulation environment according to task requirements; and a high-performance simulation framework is conducted, which provides strong support for different application modes, such as parallel hyper-real-time and distributed simulation deduction. The unified description, organization and management method of model and data resources …

The Simulation Assessment Of Availability For K/N Redundancy System Considering Failure Relevance Of Components, Haidong Du, Junhai Cao, Fusheng Liu, Xu Dan

Journal of System Simulation

Abstract: For the limitations existing in the system availability assessment based on the failure independent hypothesis,the availability assessment model for k/N system based on Copula function theory is built.A reliability evaluation method of fault-related system on the foundation of Agent technique is proposed. The completion of the simulation model from component entity to equipment entity resolves the question of reliability assessment existing in k/N system considering the effects of components relevance. And last, the evaluation results of system availability under different spare parts schemes are given under different material support program, the research results show that the relevance existing …

Simulation Research On Pedestrian Evacuation Path Selection In The Metro Station, Sun Di, Zhou Jin, Xueying Gao, Ting Jiao, Lixian Zhao

Journal of System Simulation

Abstract: As the underground environment is multilayered, more confined space underground, there are many services and facilities, so that when people evacuate the subway, they will have a variety of features and choices. Path probability selection of underground pedestrian evacuation is discussed. In the first stage, models are used to plan several routes. In the second stage, according to the data of real time passenger flow of the railway station, the density of passenger flow is taken as a variable to obtain the time of pedestrian evacuation through different facilities. The traffic capacity of every passage and facility …

Pshev Cold Start Emission Simulation Based On Electric Heated Catalyst Pre-Heating, Deng Tao, Haoyuan Yu, Zhifei Li, Haixin Tan

Journal of System Simulation

Abstract: In order to reduce the emissions of the plug-in series hybrid electric vehicle (PSHEV) during the cold start phase, a vehicle model on PSHEV is established and a dynamic model of electrically heated catalyst system (EHCS) based on optimization and control strategy of engine start-stop is built. The PSHEV energy management control strategy based on EHCS preheating is proposed. The influence of different pre-heating power on EHCS temperature is simulated. By comparing SOC value of the control strategy with the original control strategy; and comparative analysis of cold start emissions of three elements catalyst under three strategies of pre-heating, …

Research On Hwil Simulation Of Rf/Ir Dual-Mode Sensors Based On Compact Antenna, Gao Yang, Ma Jing, Huiyang Qu, Qun Wei, Jindong Fei

Journal of System Simulation

Abstract: The advent of RF/IR dual-mode sensor technology in the more and more completed detecting environment has led to the requirement of simulation tools that are necessary to test dual-mode sensor. The hardware-in-the-loop simulation experiment and test of the radio frequency/infrared composite sensor are carried out.A RF/IR dual-mode simulation method based on the Compact antenna test ranges is proposed here. This system consists of IR simulator, RF simulator, beam-combiner etc. The testing result shows that RF/IR dual-mode simulation system has abilities of IR transmission and RF reflection, and could be used in RF/IR dual-mode sensor simulation.