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2014

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Articles 5371 - 5400 of 7238

Full-Text Articles in Engineering

Location Management And Hybrid Geo-Routing For Urban Vehicular Networks, Aisling O'Driscoll Jan 2014

Location Management And Hybrid Geo-Routing For Urban Vehicular Networks, Aisling O'Driscoll

Theses

In recent years the motivation for comfort applications e.g. infotainment, file exchange and vehicle to vehicle (V2V) multiplayer gaming amongst others, has emerged as an active area of vehicular communications and network research. The success of such applications relies on the ability of a geo-routing protocol to deliver communication packets in a frequently disconnected communication environment. To do this, the location of the destination vehicle must first be determined and secondly, must reliably deliver the packet from source to destination. To determine the location of a target vehicle towards which packets can be forwarded, geo-routing algorithms utilise a location service …

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Classification Of Irish Beaches, Johnjoe O'Sullivan Jan 2014

Classification Of Irish Beaches, Johnjoe O'Sullivan

Theses

This project aims to develop a beach classification model that has been validated for use on Irish beaches. Beach classification models have been developed over the past six decades as a means of identifying the sedimentological, morphological and hydrodynamic beach features that are present on beaches. Beach classification models have been pioneered by researchers for beaches in Australia and have been subject to continuous development through the monitoring and research of beaches along the Australian coastline. Recently a similar model been developed for England and Wales based on data collected from beaches along the coastline. This report will investigate the …

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A Technical And Economic Appraisal Of Insulation Retrofits, Niamh O'Brien Jan 2014

A Technical And Economic Appraisal Of Insulation Retrofits, Niamh O'Brien

Theses

The main aim of this literature review is to further develop the project brief and to examine what research has previously been undertaken in the field of thermal conductivity and retrofitting insulation. The basis of this project is to determine the effect of moisture in domestic cavity walls on the effectiveness of retrofitted insulation. The research began by highlighting the reasoning behind the need for insulation within domestic dwellings within Ireland and the guiding legislation in place in relation to this. Carrying on from this, the current methods used to retrofit insulation were examined, along with the types of insulation …

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A Technical And Economic Appraisal Of Insulation Retrofits, Niamh O'Brien Jan 2014

A Technical And Economic Appraisal Of Insulation Retrofits, Niamh O'Brien

Theses

The main aim of this literature review is to further develop the project brief and to examine what research has previously been undertaken in the field of thermal conductivity and retrofitting insulation. The basis of this project is to determine the effect of moisture in domestic cavity walls on the effectiveness of retrofitted insulation. The research began by highlighting the reasoning behind the need for insulation within domestic dwellings within Ireland and the guiding legislation in place in relation to this. Carrying on from this, the current methods used to retrofit insulation were examined, along with the types of insulation …

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A Calderón Preconditioner For The Electric Field Integral Equation With Layered Medium Green's Function, Yongpin P. Chen, Sheng Sun, Lijun Jiang, Weng Cho Chew Jan 2014

A Calderón Preconditioner For The Electric Field Integral Equation With Layered Medium Green's Function, Yongpin P. Chen, Sheng Sun, Lijun Jiang, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

A Calderón preconditioner is developed for the analysis of electromagnetic scattering of perfect electrically conducting (PEC) objects embedded in a layered medium. The electric field integral equation (EFIE) is formulated with the kernel of layered medium Green's function to account for the effects from the multilayered background. The Calderón projector is derived based on the general source-field relationship and the extinction theorem for inhomogeneous environment in electromagnetic theory. The Calderón identities can be naturally deduced based on this projector, which is then leveraged to precondition the EFIE with layered kernel. An alternative implementation is then proposed to make the implementation …

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Fast Feature Selection In A Gpu Cluster Using The Delta Test, Alberto Guillén, M. Isabel García Arenas, Mark Van Heeswijk, Dusan Sovilj, Amaury Lendasse, Luis Javier Herrera, Héctor Pomares, Ignacio Rojas Jan 2014

Fast Feature Selection In A Gpu Cluster Using The Delta Test, Alberto Guillén, M. Isabel García Arenas, Mark Van Heeswijk, Dusan Sovilj, Amaury Lendasse, Luis Javier Herrera, Héctor Pomares, Ignacio Rojas

Engineering Management and Systems Engineering Faculty Research & Creative Works

Feature or Variable Selection Still Remains an Unsolved Problem, Due to the Infeasible Evaluation of All the Solution Space. Several Algorithms based on Heuristics Have Been Proposed So Far with Successful Results. However, These Algorithms Were Not Designed for Considering Very Large Datasets, Making their Execution Impossible, Due to the Memory and Time Limitations. This Paper Presents an Implementation of a Genetic Algorithm that Has Been Parallelized using the Classical Island Approach, But Also Considering Graphic Processing Units to Speed Up the Computation of the Fitness Function. Special Attention Has Been Paid to the Population Evaluation, as Well as to …

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Long-Term Time Series Prediction Using Op-Elm, Alexander Grigorievskiy, Yoan Miche, Anne Mari Ventelä, Eric Séverin, Amaury Lendasse Jan 2014

Long-Term Time Series Prediction Using Op-Elm, Alexander Grigorievskiy, Yoan Miche, Anne Mari Ventelä, Eric Séverin, Amaury Lendasse

Engineering Management and Systems Engineering Faculty Research & Creative Works

In This Paper, an Optimally Pruned Extreme Learning Machine (Op-Elm) is Applied to the Problem of Long-Term Time Series Prediction. Three Known Strategies for the Long-Term Time Series Prediction I.e. Recursive, Direct and Dirrec Are Considered in Combination with Op-Elm and Compared with a Baseline Linear Least Squares Model and Least-Squares Support Vector Machines (Ls-Svm). among These Three Strategies Dirrec is the Most Time Consuming and its Usage with Nonlinear Models Like Ls-Svm, Where Several Hyperparameters Need to Be Adjusted, Leads to Relatively Heavy Computations. It is Shown that Op-Elm, Being Also a Nonlinear Model, Allows Reasonable Computational Time for …

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Conquering Complexity: Challenges And Opportunities: Preface, Cihan H. Dagli Jan 2014

Conquering Complexity: Challenges And Opportunities: Preface, Cihan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

No abstract provided.

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How To Rein In The Volatile Actor: A New Bounded Perspective, Abhijit Gosavi Jan 2014

How To Rein In The Volatile Actor: A New Bounded Perspective, Abhijit Gosavi

Engineering Management and Systems Engineering Faculty Research & Creative Works

Actor-critic algorithms are amongst the most well-studied reinforcement learning algorithms that can be used to solve Markov decision processes (MDPs) via simulation. Unfortunately, the parameters of the so-called "actor" in the classical actor-critic algorithm exhibit great volatility - getting unbounded in practice, whence they have to be artificially constrained to obtain solutions in practice. The algorithm is often used in conjunction with Boltzmann action selection, where one may have to use a temperature to get the algorithm to work, but the convergence of the algorithm has only been proved when the temperature equals 1. We propose a new actor-critic algorithm …

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Carbon Constrained Integrated Inventory Control And Truckload Transportation With Heterogeneous Freight Trucks, Dinçer Konur Jan 2014

Carbon Constrained Integrated Inventory Control And Truckload Transportation With Heterogeneous Freight Trucks, Dinçer Konur

Engineering Management and Systems Engineering Faculty Research & Creative Works

This paper analyzes an integrated inventory control and transportation problem with environmental considerations. Particularly, explicit transportation modeling is included with inventory control decisions to capture per truck costs and per truck capacities. Furthermore, a carbon cap constraint on the total emissions is formulated by considering emission characteristics of various trucks that can be used for inbound transportation. Due to complexity of the resulting optimization problem, a heuristic search method is proposed based on the properties of the problem. Numerical studies illustrate the efficiency of the proposed method. Furthermore, numerical examples are presented to show that both costs and emissions can …

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Study Of The Use Of A Genetic Algorithm To Improve Networked System-Of-Systems Resilience, Charles O. Adler, Cihan H. Dagli Jan 2014

Study Of The Use Of A Genetic Algorithm To Improve Networked System-Of-Systems Resilience, Charles O. Adler, Cihan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

Large scale failures or degradation resulting from smaller initial failures or disruptions in networked system-of-systems are an issue in multiple areas - for example cascading failures in electrical power grids or large disruptions in national air traffic due to local or regional weather conditions. The system architecture can have a significant impact on system-of-systems susceptibility to large scale failures. The study presented in this paper uses a simple interdependent networked system-of-systems failure model, integrated into a unique objective function that addresses both the overall level of failure and the rate of failure progression, and a genetic algorithm to demonstrate an …

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Computational Complexity Measures For Many-Objective Optimization Problems, David M. Curry, Cihan H. Dagli Jan 2014

Computational Complexity Measures For Many-Objective Optimization Problems, David M. Curry, Cihan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

Multi-objective Optimization Problems (MOPs) are commonly encountered in the study and design of complex systems. Pareto dominance is the most common relationship used to compare solutions in MOPs, however as the number of objectives grows beyond three, Pareto dominance alone is no longer satisfactory. These problems are termed "Many-Objective Optimization Problems (MaOPs)". While most MaOP algorithms are modifications of common MOP algorithms, determining the impact on their computational complexity is difficult. This paper defines computational complexity measures for these algorithms and applies these measures to a Multi-Objective Evolutionary Algorithm (MOEA) and its MaOP counterpart.

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On The Flexibility Of Systems In System Of Systems Architecting, Dincer Konur, Hadi Farhangi, Cihan H. Dagli Jan 2014

On The Flexibility Of Systems In System Of Systems Architecting, Dincer Konur, Hadi Farhangi, Cihan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

System of Systems (SoS) architecting requires analyzing a set of individual but interconnected systems simultaneously in order to build a communicating SoS, which can provide the capabilities needed. In general, the systems can provide a set of capabilities and the SoS architect needs to decide which systems to include in the SoS so that each capability is provided by at least one system. In this case, the systems are inflexible, i.e., a selected system will contribute to the SoS with all the capabilities it can provide. On the other hand, if SoS architect can incentivize systems to contribute specific capabilities …

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A Hybrid Genetic Algorithm And Particle Swarm Optimization With Type-2 Fuzzy Sets For Generating Systems Of Systems Architectures, Siddhartha Agarwal, Louis E. Pape, Cihan H. Dagli Jan 2014

A Hybrid Genetic Algorithm And Particle Swarm Optimization With Type-2 Fuzzy Sets For Generating Systems Of Systems Architectures, Siddhartha Agarwal, Louis E. Pape, Cihan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

Both modeling and simulating a system of systems (SoS) are difficult due not only to a changing environment but also the unique behavior that is linked to different participating systems. Generating architectures for a SoS is a multi-objective optimization problem with large number of variables and constraints. The paper presents several of computational intelligence techniques that can generate SoS architectures, such as genetic algorithms (GA), and particle swarm optimization (PSO) combined with Type 2 Fuzzy logic nets. The Maritime search and rescue (SAR) were used as a SoS domain scenario to both implement and demonstrate the architecting methodology. SAR utilizes …

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A Static Voltage Security Region For Centralized Wind Power Integration-Part Ii: Applications, Tao Ding, Qinglai Guo, Rui Bo, Hongbin Sun, Boming Zhang, Tianen Huang Jan 2014

A Static Voltage Security Region For Centralized Wind Power Integration-Part Ii: Applications, Tao Ding, Qinglai Guo, Rui Bo, Hongbin Sun, Boming Zhang, Tianen Huang

Electrical and Computer Engineering Faculty Research & Creative Works

In Part I of this work, a static voltage security region was introduced to guarantee the safety of wind farm reactive power outputs under both base conditions and N-1 contingency. In this paper, a mathematical representation of the approximate N-1 security region has further studied to provide better coordination among wind farms and help prevent cascading tripping following a single wind farm trip. Besides, the influence of active power on the security region is studied. The proposed methods are demonstrated for N-1 contingency cases in a nine-bus system. The simulations verify that the N-1 security region is a small subset …

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Overexpression Of Dcf1 Inhibits Glioma Through Destruction Of Mitochondria And Activation Of Apoptosis Pathway, Yuqiong Xie, Qang Li, Qingbo Yang Jan 2014

Overexpression Of Dcf1 Inhibits Glioma Through Destruction Of Mitochondria And Activation Of Apoptosis Pathway, Yuqiong Xie, Qang Li, Qingbo Yang

Electrical and Computer Engineering Faculty Research & Creative Works

Gliomas are the most common brain tumors affecting the central nervous system and are associated with a high mortality rate. DCF1 is a membrane protein that was previously found to play a role in neural stem cell differentiation. In the present study, we found that overexpression of dcf1 significantly inhibited cell proliferation, migration, and invasion and dramatically promoted apoptosis in the glioblastoma U251 cell line. DCF1 deletion mutations in the functional region showed that the complete structure of DCF1 was necessary for apoptosis. Furthermore, significantly lower tumorigenicity was observed in athymic nude mice by transplanting U251 cells overexpressing dcf1. To …

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Assessment Of Corn Stover Torrefaction For On-Farm Biochar Production, Christina M. Gerometta Jan 2014

Assessment Of Corn Stover Torrefaction For On-Farm Biochar Production, Christina M. Gerometta

Electronic Theses and Dissertations

Torrefaction is a thermochemical pretreatment process that is typically achieved by slowly heating biomass (<50°C/min) within the temperature range of 200 – 300°C under an inert atmosphere. This process yields a storable solid product with enhanced fuel characteristics that are influenced by the ligno-cellulosic composition of the original feedstock and the imposed torrefaction conditions (time and temperature). This study is an assessment of corn stover properties that are relevant for designing an on-farm torrefaction system. The first portion of this study compared the thermal decomposition behaviors of corn stover fractions (leaf, stalk, cob) to the respective ligno-cellulosic composition using thermo-gravimetric analysis. It was found that the thermal decomposition pattern correlates to the structure and ratio of ligno-cellulosic polymers and provides design guidelines for an on-farm torrefaction system capable of handling large quantities of mixed fraction stover. The second part of this study investigated the effects of torrefaction time and temperature on the mass and energy yield of mixed fraction corn stover using a 46.3 L batch style reactor. It was found that longer reaction times and higher temperatures were required to obtain mass and energy yields similar to those found using lab-scale reactors and finely milled samples. Non-uniform torrefaction occurred between fractions due to chemical composition of each fraction and proximity to the heating elements.

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Data Pattern Based Electromagnetic Interference Modeling For Ic Packaging, Nick K.H. Huang, Tao Wang, Li (Lijun) Jun Jiang, X. Y. Xiong Jan 2014

Data Pattern Based Electromagnetic Interference Modeling For Ic Packaging, Nick K.H. Huang, Tao Wang, Li (Lijun) Jun Jiang, X. Y. Xiong

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic interference (EMI) is becoming more serious when the data rate of the digital system continues increasing. However, its modeling and analysis are very challenging. In this paper, a novel electromagnetic superposition method is developed to model the IC packaging electromagnetic emission. It employs the equivalence principle to obtain the electromagnetic field response over a broad spectrum. Then it uses the linear property of the passive parasitic system to superpose the contribution of different signals on the packaging. As a result, with certain pre-calculations, it is convenient to compute the electromagnetic emission efficiently from different signals with various data pattern …

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Overhead High-Voltage Transmission-Line Current Monitoring By Magnetoresistive Sensors And Current Source Reconstruction At Transmission Tower, X. Sun, Q. Huang, L. (Lijun) J. Jiang, P. W.T. Pong Jan 2014

Overhead High-Voltage Transmission-Line Current Monitoring By Magnetoresistive Sensors And Current Source Reconstruction At Transmission Tower, X. Sun, Q. Huang, L. (Lijun) J. Jiang, P. W.T. Pong

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a novel current monitoring technology based on magnetic field sensing at a transmission tower for overhead high-voltage transmission lines (HVTLs), which can accurately measure phase current parameters in real time. This technology is based on the phenomenon that the magnetic field distribution at the top level of a transmission tower can reflect the operation states of the transmission lines including current amplitude and phase angle imbalances. A current source reconstruction method based on stochastic optimization strategy was developed to reconstruct the electrical parameters from the magnetic field emanated by the overhead transmission lines. This concept of current …

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A New Efficient Method For Analysis Of Finite Periodic Structures, Xiaoyan Y.Z. Xiong, Ling Ling Meng, Li (Lijun) Jun Jiang, Wei E.I. Sha Jan 2014

A New Efficient Method For Analysis Of Finite Periodic Structures, Xiaoyan Y.Z. Xiong, Ling Ling Meng, Li (Lijun) Jun Jiang, Wei E.I. Sha

Electrical and Computer Engineering Faculty Research & Creative Works

The electromagnetic modeling of practical finite periodic structures is a topic of growing interest. Due to the truncation of the infinite periodic structures, surface waves will be excited and localized near the discontinuous interfaces leading to the edge effect of finite structures. In this work, surface waves are numerically disentangled from the propagating Bloch waves contributions. Based on the universally exponential decay feature of the surface waves, a novel method is developed by connecting the solution to the large finite periodic structure with that to a relatively small one resulting in low complexity and memory consumption. The method numerically reconstructs …

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A Rigorous Approach For The Radiated Emission Characterization Based On The Spherical Magnetic Field Scanning, Ping Li, Li (Lijun) Jun Jiang Jan 2014

A Rigorous Approach For The Radiated Emission Characterization Based On The Spherical Magnetic Field Scanning, Ping Li, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic radiated emissions from antennas, printed circuit boards (PCBs), and electronic devices are becoming increasingly critical to today's IC electromagnetic compatibility and interference properties. In this paper, a rigorous characterization approach is proposed. The electromagnetic field sampling over a spherical testing surface is applied to obtain the radiated magnetic field of the device under test (DUT) placed at the center of the sampling region. Using the dyadic Green's function (DGF) and Huygens' principle, the transformation from the sampled spherical tangential field to the far field is directly computed without resorting to the conventional inverse algorithm. The DGF considers the existence …

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Generalized Modal Expansion And Reduced Modal Representation Of 3-D Electromagnetic Fields, Qi I. Dai, Yat Hei Lo, Weng Cho Chew, Yang G. Liu, Li (Lijun) Jun Jiang Jan 2014

Generalized Modal Expansion And Reduced Modal Representation Of 3-D Electromagnetic Fields, Qi I. Dai, Yat Hei Lo, Weng Cho Chew, Yang G. Liu, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

A generalized modal expansion theory for investigating arbitrary 3-D bounded and unbounded electromagnetic fields is presented. When an inhomogeneity is enclosed with impenetrable boundaries, the field excited by arbitrary sources is expanded with a complete set of eigenmodes, which are classified into trapped modes and radiation modes. As the boundaries tend to infinity, trapped modes remain unchanged, while radiation modes form a continuum. To illustrate the theory, several real-life structures are investigated with a conformal finite-difference technique in the frequency domain. Perfectly matched layers (PMLs) are imposed at finite extent to emulate the unbounded problems. Numerical examples show that, only …

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Model Order Reduction For Quantum Transport Simulation Of Band-To-Band Tunneling Devices, Jun Z. Huang, Lining Zhang, Weng Cho Chew, Chi Yung Yam, Li (Lijun) Jun Jiang, Guan Hua Chen, Mansun Chan Jan 2014

Model Order Reduction For Quantum Transport Simulation Of Band-To-Band Tunneling Devices, Jun Z. Huang, Lining Zhang, Weng Cho Chew, Chi Yung Yam, Li (Lijun) Jun Jiang, Guan Hua Chen, Mansun Chan

Electrical and Computer Engineering Faculty Research & Creative Works

Simulations of nanoelectronic devices with nonequilibrium Greens function are computationally very intensive, in particular, when combined with multiband approaches, such as the k p methods. To reduce the cost and make the simulation of realistic devices tractable, we have developed a model order reduction method for the simulation of hole transport in silicon nanowires using three- and six-band k p models. It is shown in this paper that, with a spurious band elimination process, the method can be readily extended to the eight-band case that enables us to simulate band-to-band tunneling devices. The method is demonstrated via constructing reduced models …

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Using Acoustic Emission Monitoring For Energy-Based Fatigue Life Prediction, Sepehr Nesaei Jan 2014

Using Acoustic Emission Monitoring For Energy-Based Fatigue Life Prediction, Sepehr Nesaei

Electronic Theses and Dissertations

The study of fatigue and fracture mechanics is crucial to the health monitoring and overall safety of aerospace and civil structures. The materials used to manufacture these industry parts have inherent anomalies that eventually grow under cyclic loadings during regular operation. The ASTM and/or military testing guidelines used to analyze and qualify structures and materials for use are costly and time consuming. Therefore, any additional methods or knowledge that can be used to reduce the number of tests will be useful to the industry to avoid unnecessary costs. Acoustic emission (AE) monitoring is currently used in many applications to assess …

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Event-Triggered Optimal Regulation Of Uncertain Linear Discrete-Time Systems By Using Q-Learning Scheme, Avimanyu Sahoo, S. Jagannathan Jan 2014

Event-Triggered Optimal Regulation Of Uncertain Linear Discrete-Time Systems By Using Q-Learning Scheme, Avimanyu Sahoo, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, an event-triggered optimal adaptive regulation of an uncertain linear discrete time system is proposed. This scheme solves the optimal control in a forward in- time and online manner by using both dynamic programming and Q learning. First, the time varying action dependent value or the Q-function is estimated online by an adaptive value function estimator (VFE) with event-based state vector and a time dependent basis function. The estimated value function parameters are subsequently used to generate the optimal control gain matrix. Further, aperiodic tuning law for the VFE parameters is proposed not only to estimate the parameters …

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A Fault Prediction Scheme For Takagi-Sugeno Fuzzy Systems With Immeasurable Premise Variables And Disturbance, Balaje T. Thumati, Jagannathan Sarangapani Jan 2014

A Fault Prediction Scheme For Takagi-Sugeno Fuzzy Systems With Immeasurable Premise Variables And Disturbance, Balaje T. Thumati, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

As explained in the literature, it is very hard to measure premise variables of a Takagi-Sugeno (TS) fuzzy system. Therefore, in this paper, a fault detection and prediction (FDP) scheme is designed for a class of TS fuzzy systems with immeasurable (unknown) premise variables and external disturbances. A fault detection (FD) observer is designed to approximate the system output and the premise variables. Subsequently, a FD residual is generated by comparing the observer output with respect to the system output. The FD residual is evaluated to detect any faults in the system. Further, time-to-failure (TTF) of the TS fuzzy system …

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Phasor Measurement Unit Placement For Identifying Power Line Outages In Wide-Area Transmission System Monitoring, Hao Zhu, Yiyu Shi Jan 2014

Phasor Measurement Unit Placement For Identifying Power Line Outages In Wide-Area Transmission System Monitoring, Hao Zhu, Yiyu Shi

Electrical and Computer Engineering Faculty Research & Creative Works

Phasor measurement units (PMUs) are widely recognized to be instrumental for enhancing the power system situational awareness - a key step toward the future power grid. With limited PMU resources and high installation costs, it is of great importance to develop strategic PMU deployment methods. This paper focuses on optimally selecting PMU locations for monitoring transmission line status across the wide-area grid. To bypass the combinatorial search involved, a linear programming reformulation is first developed to provide an upper bound estimate for the global optimum. Furthermore, a greedy heuristic method is adopted with the complexity only linearly in the number …

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Indoor Positioning System Using Geo-Magnetic Field, Abhinav Saxena, Maciej Zawodniok Jan 2014

Indoor Positioning System Using Geo-Magnetic Field, Abhinav Saxena, Maciej Zawodniok

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper we address the problem of non-Adversarial co-operative localization using the Earth's ambient magnetic field. We demonstrate the feasibility of using magnetic field to perform localization and tracking. A three-Axis magnetic field sensor is employed to locate and track a target. The algorithm estimates the position using the magnitude of the current magnetic field readings. Our technique depends on the local distortions in the Earth's magnetic field created by presence of various magnetic or metallic objects in the local workspace. These objects may be manmade or naturally occurring. The magnetic field data corresponding to known locations is stored …

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Localization And Tracking Of Objects Using Cross-Correlation Of Shadow Fading Noise, M. R. Basheer, S. Jagannathan Jan 2014

Localization And Tracking Of Objects Using Cross-Correlation Of Shadow Fading Noise, M. R. Basheer, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

Multipath and shadow fading are the primary cause for positioning errors in a Received Signal Strength Indicator (RSSI) based localization scheme. While fading, in general, is detrimental to localization accuracy, cross-correlation and divergence properties of shadow fading residuals may be utilized to improve localization and tracking accuracy of mobile IEEE 802.15.4 transmitters. Therefore, this paper begins by presenting a stochastic filter that models the fast-changing multipath fading as a mean reverting Ornstein-Uhlenbeck (OU) process followed by a Generalized Auto Regressive Conditional Heteroskedasticity (GARCH) filtering to isolate the slow changing shadow fading residuals from measured RSSI values. Subsequently, a novel wireless …

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Nonlinear Development And Secondary Instability Of Traveling Crossflow Vortices, Fei Li, Meelan M. Choudhari, Lian Duan, Chau-Lyan Chang Jan 2014

Nonlinear Development And Secondary Instability Of Traveling Crossflow Vortices, Fei Li, Meelan M. Choudhari, Lian Duan, Chau-Lyan Chang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Building upon the prior research targeting the laminar breakdown mechanisms associated with stationary crossflow instability over a swept-wing configuration, this paper investigates the secondary instability of traveling crossflow modes as an alternate scenario for transition. For the parameter range investigated herein, this alternate scenario is shown to be viable unless the initial amplitudes of the traveling crossflow instability are lower than those of the stationary modes by considerably more than one order of magnitude. The linear growth predictions based on the secondary instability theory are found to agree well with both parabolized stability equations and direct numerical simulation, and the …

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