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2012

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Articles 391 - 420 of 12196

Full-Text Articles in Physical Sciences and Mathematics

User Identification For Opportunistic Ofdm-Based Multiuser Wireless Communications, Hang Li, Qinghua Guo, Defeng (David) Huang, Yingjun (Angela) Zhang Dec 2012

User Identification For Opportunistic Ofdm-Based Multiuser Wireless Communications, Hang Li, Qinghua Guo, Defeng (David) Huang, Yingjun (Angela) Zhang

Dr Qinghua Guo

Multiuser diversity can be employed in wireless communications to significantly improve system performance by scheduling the channel to the user with the best instantaneous channel-state information (CSI). Conventionally, all users’ CSI must be available at the base station (BS) to achieve the benefit of multiuser diversity, thereby inducing enormous system overhead. To solve the overhead issue, we propose a user identification approach (UIDA) in a generic wireless network and demonstrate its application in the orthogonal frequency-division multiplexing (OFDM) system and the multiple-input multiple-output OFDM (MIMO-OFDM) system. In the UIDA, to find the user with the best CSI, all active users …

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A Lotto Systems Problem, Kenneth Russell, David Atherton Griffiths Dec 2012

A Lotto Systems Problem, Kenneth Russell, David Atherton Griffiths

Professor David Griffiths

No abstract provided.

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Performance Of Java Middleware - Java Rmi, Jaxrpc, And Corba, N. A. B. Gray Dec 2012

Performance Of Java Middleware - Java Rmi, Jaxrpc, And Corba, N. A. B. Gray

Associate Professor Neil Gray

Developers of distributed Java systems can now choose among Java-RMI, CORBA, and Web-Service (JAXRPC) middleware technologies. Performance is one factor that has to be considered in choosing the appropriate technology for a particular application. The results presented in this paper show that the nature of response data has a greater impact on relative performance than has been allowed for in most previous studies. Relative performances of the technologies as measured on simple requests and responses are not representative of the behaviour that can be expected in practical applications.

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Pricing Of Volatility Derivatives Using 3/2-Stochastic Models, Joanna Goard Dec 2012

Pricing Of Volatility Derivatives Using 3/2-Stochastic Models, Joanna Goard

Dr Joanna Goard

Analytic solutions are found for prices of both variance and volatility swaps and VIX options under new 3/2- stochastic models for the dynamics of the underlying assets. The main features of the new stochastic differential equations are an empirically validated cv3/2 diffusion term, a nonlinear drift providing a balancing effect of a stronger mean reversion with high volatility, and for the case of the variance and volatility swaps, a free function of time as a moving target in the reversion term, allowing additional flexibility for model calibration against market data.

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Data Curation Is For Everyone! The Case For Master's And Baccalaureate Institutional Engagement With Data Curation, Yasmeen Shorish Dec 2012

Data Curation Is For Everyone! The Case For Master's And Baccalaureate Institutional Engagement With Data Curation, Yasmeen Shorish

Yasmeen Shorish

This article describes the fundamental challenges to data curation, how these challenges may be compounded for smaller institutions, and how data management is an essential and manageable component of data curation. Data curation is often discussed within the confines of large, research universities. As a result, master’s and baccalaureate institutions may be left with the impression that they cannot engage with data curation. However, by proactively engaging with faculty, libraries of all sizes can build closer relationships and help educate faculty on data documentation and organization best practices. Experiences from one master’s comprehensive institution as it engages with data management …

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A Sparse Implementation Of The Average Information Algorithm For Factor Analytic And Reduced Rank Variance Models, R Thompson, Brian Cullis, A Smith, Arthur Gilmour Dec 2012

A Sparse Implementation Of The Average Information Algorithm For Factor Analytic And Reduced Rank Variance Models, R Thompson, Brian Cullis, A Smith, Arthur Gilmour

Dr Arthur Gilmour

Factor analytic variance models have been widely considered for the analysis of multivariate data particularly in the psychometrics area. Recently Smith, Cullis & Thompson (2001) have considered their use in the analysis of multi-environment data arising from plant improvement programs. For these data, the size of the problem and the complexity of the variance models chosen to account for spatial heterogeneity within trials implies that standard algorithms for fitting factor analytic models can be computationally expensive. This paper presents a sparse implementation of the average information algorithm (Gilmour, Thompson & Cullis, 1995) for fitting factor analytic and reduced rank variance …

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Estimating Variance Components And Predicting Breeding Values For Eventing Disciplines And Grades In Sport Horses, I Stewart, I.M White, Arthur Gilmour, R Thompson, J Woolliams, S Brotherstone Dec 2012

Estimating Variance Components And Predicting Breeding Values For Eventing Disciplines And Grades In Sport Horses, I Stewart, I.M White, Arthur Gilmour, R Thompson, J Woolliams, S Brotherstone

Dr Arthur Gilmour

Eventing competitions in Great Britain (GB) comprise three disciplines, each split into four grades, yielding 12 discipline-grade traits. As there is a demand for tools to estimate (co)variance matrices with a large number of traits, the aim of this work was to investigate different methods to produce large (co)variance matrices using GB eventing data. Data from 1999 to 2008 were used and penalty points were converted to normal scores. A sire model was utilised to estimate fixed effects of gender, age and class, and random effects of sire, horse and rider. Three methods were used to estimate (co)variance matrices. Method …

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Estimation In A Multiplicative Mixed Model Involving A Genetic Relationship Matrix, Alison M. Kelly, Brian R. Cullis, Arthur R. Gilmour, John A. Eccleston, Robin Thompson Dec 2012

Estimation In A Multiplicative Mixed Model Involving A Genetic Relationship Matrix, Alison M. Kelly, Brian R. Cullis, Arthur R. Gilmour, John A. Eccleston, Robin Thompson

Dr Arthur Gilmour

Genetic models partitioning additive and non-additive genetic effects for populations tested in replicated multi-environment trials (METs) in a plant breeding program have recently been presented in the literature. For these data, the variance model involves the direct product of a large numerator relationship matrix A, and a complex structure for the genotype by environment interaction effects, generally of a factor analytic (FA) form. With MET data, we expect a high correlation in genotype rankings between environments, leading to non-positive definite covariance matrices. Estimation methods for reduced rank models have been derived for the FA formulation with independent genotypes, and we …

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An Examination Of The Efficiency Of Australian Crop Variety Evaluation Programmes, Brian R. Cullis, A B. Smith, C Hunt, Arthur R. Gilmour Dec 2012

An Examination Of The Efficiency Of Australian Crop Variety Evaluation Programmes, Brian R. Cullis, A B. Smith, C Hunt, Arthur R. Gilmour

Dr Arthur Gilmour

In this paper we present the analysis of yield data from a broad cross-section of crop variety evaluation programmes (CVEP) conducted in Australia. The main sources of variety by environment interaction are ` non-static ' interactions, namely those linked to seasonal influences. These contributed an average of 41.3% of the total variance. In contrast the static component accounts for only 5.3% of the total. We develop methods for determining the relative accuracy of CVEP based on selection of newly promoted entries. The accuracy of the current testing regimes for the Australian CVEP under study is determined. The accuracy of alternative …

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Symmetry Solutions For Transient Solute Transport In Unsaturated Soils With Realistic Water Profile, Maureen Edwards, R Joel Moitsheki, Philip Broadbridge Dec 2012

Symmetry Solutions For Transient Solute Transport In Unsaturated Soils With Realistic Water Profile, Maureen Edwards, R Joel Moitsheki, Philip Broadbridge

Dr Maureen Edwards

No abstract provided.

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The Effect Of Incomplete Mixing Upon Quadratic Autocatalysis, Ahmed Hussein Msmali, Mark Nelson, Maureen Edwards Dec 2012

The Effect Of Incomplete Mixing Upon Quadratic Autocatalysis, Ahmed Hussein Msmali, Mark Nelson, Maureen Edwards

Dr Maureen Edwards

We analyse a model for a continuously stirred tank reactor with imperfect mixing in which the reactor is represented by two well mixed compartments with material transfer between them. These reactors represent `highly agitated' and `less agitated' regions. The chemical model used is a quadratic autocatalytic scheme with linear decay of the autocatalyst. We investigate how the reactor performance depends upon the degree of mixing in the reactor and the size of the less agitated region. Surprisingly, the performance of the reactor with sufficiently small values of mixing is inferior to that with no mixing between the compartments.

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Group Invariant Solutions For Two Dimensional Solute Transport Under Realistic Water Flows, Maureen Edwards, R Joel Moitsheki, Philip Broadbridge Dec 2012

Group Invariant Solutions For Two Dimensional Solute Transport Under Realistic Water Flows, Maureen Edwards, R Joel Moitsheki, Philip Broadbridge

Dr Maureen Edwards

No abstract provided.

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Lie Group Symmetry Analysis Of Transport In Porous Media With Variable Transmissivity, James Hill, Maureen Edwards, A P S Selvadurai Dec 2012

Lie Group Symmetry Analysis Of Transport In Porous Media With Variable Transmissivity, James Hill, Maureen Edwards, A P S Selvadurai

Dr Maureen Edwards

We determine the Lie group symmetries of the coupled partial differential equations governing a novel problem for the transient flow of a fluid containing a solidifiable gel, through a hydraulically isotropic porous medium. Assuming that the permeability ($K^*$) of the porous medium is a function of the gel concentration ($c^*$), we determine a number of exact solutions corresponding to the cases where the concentration-dependent permeability is either arbitrary or has a power law variation or is a constant. Each case admits a number of distinct Lie symmetries and the solutions corresponding to the optimal systems are determined. Some typical concentration …

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Modelling Pattern Formation In Plants, M P. Edwards, S Pereverzyev, R S. Anderssen Dec 2012

Modelling Pattern Formation In Plants, M P. Edwards, S Pereverzyev, R S. Anderssen

Dr Maureen Edwards

Performing simulations with simple models is a key activity in the recovery of information about the mechanisms which underlie the observed dynamics of biological processes, such as the posi- tioning of the hairs (trichomes) on the leaves of plants. The discovery of a robust representative model is a highly non-trivial process. Without appropriate constraints to regularize the choice of a model, the non-uniqueness of possibilities is vast. As acknowledged by Young (1983) in his modelling of pea leaf development, the degree of non-uniqueness can be reduced by constraining the model to reproduce the patterns observed in mutants as well as …

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The Shape And Mechanics Of Curved Fold Origami Structures, Marcelo A. Dias, Christian Santangelo Dec 2012

The Shape And Mechanics Of Curved Fold Origami Structures, Marcelo A. Dias, Christian Santangelo

Christian Santangelo

We develop recursion equations to describe the three-dimensional shape of a sheet upon which a series of concentric curved folds have been inscribed. In the case of no stretching outside the fold, the three-dimensional shape of a single fold prescribes the shape of the entire origami structure. To better explore these structures, we derive continuum equations, valid in the limit of vanishing spacing between folds, to describe the smooth surface intersecting all the mountain folds. We find that this surface has negative Gaussian curvature with magnitude equal to the square of the fold's torsion. A series of open folds with …

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Interactions Of Aqueous Ag+ With Fulvic Acids: Mechanisms Of Silver Nanoparticle Formation And Investigation Of Stability, Nathaniel F. Adegboyega, Virender K. Sharma, Karolina Siskova, Radek Zboril, Mary Sohn, Brian J. Schultz, Sarbajit Banerjee Dec 2012

Interactions Of Aqueous Ag+ With Fulvic Acids: Mechanisms Of Silver Nanoparticle Formation And Investigation Of Stability, Nathaniel F. Adegboyega, Virender K. Sharma, Karolina Siskova, Radek Zboril, Mary Sohn, Brian J. Schultz, Sarbajit Banerjee

Chemistry and Chemical Engineering Faculty Publications

This study investigated the possible natural formation of silver nanoparticles (AgNPs) in Ag+ −fulvic acid (FA) solutions under various environmentally relevant conditions (temperature, pH, and UV light). Increase in temperature (24−90 °C) and pH (6.1−9.0) of Ag+ −Suwannee River fulvic acid (SRFA) solutions accelerated the appearance of the characteristic surface plasmon resonance (SPR) of AgNPs. The rate of AgNP formation via reduction of Ag+ in the presence of different FAs (SRFA, Pahokee Peat fulvic acid, PPFA, Nordic lake fulvic acid, NLFA) and Suwannee River humic acid (SRHA) followed the order NLFA > SRHA > PPFA > SRFA. This order was found to be …

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Trust Management Of Encrypted Data Aggregation In A Sensor Network Environment, Nayot Poolsappasit, Michael Busby, Sanjay Kumar Madria Dec 2012

Trust Management Of Encrypted Data Aggregation In A Sensor Network Environment, Nayot Poolsappasit, Michael Busby, Sanjay Kumar Madria

Computer Science Faculty Research & Creative Works

Efficient power management is vital for increasing the life of sensor nodes in wireless sensor networks (WSN). Thus, techniques such as data aggregation have been widely used in WSN to preserve nodes' energy. Despite its appealing and powerful features, data aggregation processes require a high level of security. Ensuring accuracy with aggregating data can become an issue even due to single bit errors. Hence, many encryption techniques have been proposed to secure the data aggregation process. However, once a wireless sensor is physically compromised, the keys stored on the sensor are exposed, thus rendering the cryptography useless. Moreover, most cryptographic …

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Crowdsourcing: Dynamic Data Management In Mobile P2p Networks, Sanjay Kumar Madria, Anirban Mondal Dec 2012

Crowdsourcing: Dynamic Data Management In Mobile P2p Networks, Sanjay Kumar Madria, Anirban Mondal

Computer Science Faculty Research & Creative Works

No abstract provided.

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Secure Hierarchical Data Aggregation In Wireless Sensor Networks: Performance Evaluation And Analysis, Vimal Kumar, Sanjay Kumar Madria Dec 2012

Secure Hierarchical Data Aggregation In Wireless Sensor Networks: Performance Evaluation And Analysis, Vimal Kumar, Sanjay Kumar Madria

Computer Science Faculty Research & Creative Works

Secure data aggregation in wireless sensor networks has two contrasting objectives, i) Efficiently collecting and aggregating data and ii) Aggregating the data securely. Many schemes do not take into account the possibility of corrupt aggregators and allow the aggregator to decrypt data in hop-by-hop algorithms. on the other hand, using public key cryptography for providing end to end security is not energy efficient. in this paper we present and analyze the performance of the secure hierarchical data aggregation algorithm which uses an efficient public key cryptosystem (elliptic curve cryptography) to achieve end to end security. Unlike many other secure data …

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Parametrizing Finite Frames And Optimal Frame Completions, Miriam J. Poteet Dec 2012

Parametrizing Finite Frames And Optimal Frame Completions, Miriam J. Poteet

Theses and Dissertations

Frames are used in many signal processing applications. We consider the problem of constructing every frame whose frame operator has a given spectrum and whose vectors have prescribed lengths. For a given spectrum and set of lengths, we know when such a frame exists by the Schur-Horn Theorem; it exists if and only if its spectrum majorizes its squared lengths. We provide a more constructive proof of Horn's original result. This proof is based on a new method for constructing any and all frames whose frame operator has a prescribed spectrum and whose vectors have prescribed lengths. Constructing all such …

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An Outcome-Based Approach For Ensuring Regulatory Compliance Of Business Processes, Quanjun Yin Dec 2012

An Outcome-Based Approach For Ensuring Regulatory Compliance Of Business Processes, Quanjun Yin

Electronic Thesis and Dissertation Repository

In service industries, such as healthcare, catering, tourism, etc., there exist regulations that require organisations’ service comply with the regulations. More and more regulations in the service sector are, or are aimed to be, outcome-focused regulations. An outcome prescribed in the regulation is what users should experience or achieve when the regulated business processes are compliant. Service providers need to proactively ensure that the outcomes specified in the regulations have been achieved prior to conducting the relevant part of the business or prior to inspectors discovering noncompliance. Current approaches check system requirements or business processes, not outcomes, against regulations and …

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Automatic Foreground Initialization For Binary Image Segmentation, Wei Li Dec 2012

Automatic Foreground Initialization For Binary Image Segmentation, Wei Li

Electronic Thesis and Dissertation Repository

Foreground segmentation is a fundamental problem in computer vision. A popular approach for foreground extraction is through graph cuts in energy minimization framework. Most existing graph cuts based image segmentation algorithms rely on user’s initialization. In this work, we aim to find an automatic initialization for graph cuts. Unlike many previous methods, no additional training dataset is needed. Collecting a training set is not only expensive and time consuming, but it also may bias the algorithm to the particular data distribution of the collected dataset. We assume that the foreground differs significantly from the background in some unknown feature space …

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Predicting Avian Distributions To Evaluate Spatiotemporal Overlap With Locust Control Operations In Eastern Australia, Judit K. Szabo, Pamela J. Davy, Michael Hooper, Lee Astheimer Dec 2012

Predicting Avian Distributions To Evaluate Spatiotemporal Overlap With Locust Control Operations In Eastern Australia, Judit K. Szabo, Pamela J. Davy, Michael Hooper, Lee Astheimer

Dr Pamela Davy

Locusts and grasshoppers cause considerable economic damage to agriculture worldwide. The Australian Plague Locust Commission uses multiple pesticides to control locusts in eastern Australia. Avian exposure to agricultural pesticides is of conservation concern, especially in the case of rare and threatened species. The aim of this study was to evaluate the probability of pesticide exposure of native avian species during operational locust control based on knowledge of species occurrence in areas and times of application. Using presence-absence data provided by the Birds Australia Atlas for 1998 to 2002, we developed a series of generalized linear models to predict avian occurrences …

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A Comparison Of Short-Range Molecular Order In Bent-Core And Rod-Like Nematic Liquid Crystals, S. Chakraborty, J. T. Gleeson, Antal Jákli, Samuel Sprunt Dec 2012

A Comparison Of Short-Range Molecular Order In Bent-Core And Rod-Like Nematic Liquid Crystals, S. Chakraborty, J. T. Gleeson, Antal Jákli, Samuel Sprunt

Antal Jakli

Thermotropic liquid crystals exhibit strongly temperature-dependent positional correlations among molecules in the nematic phase above the transition to a smectic-A or C phase. However, even in the absence of a lower temperature smectic phase, nematics composed of reduced symmetry molecules (bent-core mesogens, for example) reveal small angle X-ray scattering (SAXS) patterns with features similar to those associated with pretransitional smectic order. We report on a quantitative analysis and comparison of two-dimensional SAXS data on a bent-core nematic compound (lacking a smectic phase) and a rod-like nematic (exhibiting a nematic to smectic-C transition). This analysis demonstrates that a nanostructure based on …

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Seasonal Dimorphism In The Horny Bills Of Sparrows, Russell Greenberg, Matthew Etterson, Raymond M. Danner Dec 2012

Seasonal Dimorphism In The Horny Bills Of Sparrows, Russell Greenberg, Matthew Etterson, Raymond M. Danner

United States Environmental Protection Agency: Publications

Bill size is often viewed as a species-specific adaptation for feeding, but it sometimes varies between sexes, suggesting that sexual selection or intersexual competition may also be important. Hypotheses to explain sexual dimorphism in avian bill size include divergence in feeding niche or thermoregulatory demands, intrasexual selection based on increased competition among males, or female preference. Birds also show seasonal changes in bill size due to shifts in the balance between growth rate and wear, which may be due to diet or endogenous rhythms in growth. Insight into the function of dimorphism can be gained using the novel approach of …

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Synthesis And Characterization Of Copper Nanoparticles And Copper-Polymer Nanocomposites For Plasmonic Photovoltaic Applications, Sabastine Chukwuemeka Ezugwu Dec 2012

Synthesis And Characterization Of Copper Nanoparticles And Copper-Polymer Nanocomposites For Plasmonic Photovoltaic Applications, Sabastine Chukwuemeka Ezugwu

Electronic Thesis and Dissertation Repository

Deposition techniques for the fabrication of metal nanostructures influence their morphological properties, which in turn control their optical behavior. Here, copper nanoparticles (np-Cu’s) were grown using a deposition system that was specifically set up during this work, and is based on a radio frequency (RF) sputtering source that can operate at high temperature and under bias voltage. The effect of deposition conditions (RF power, chamber pressure and substrate bias voltage) on RF sputtered np-Cu’s using RF sputtering has been studied. The study included a comparison between the morphological and optical properties of as-grown np-Cu’s and thermally treated samples. The characterization …

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Hybrid Solvers For The Boolean Satisfiability Problem: An Exploration, Nicole Nelson Dec 2012

Hybrid Solvers For The Boolean Satisfiability Problem: An Exploration, Nicole Nelson

Theses and Dissertations

The Boolean Satisfiability problem (SAT) is one of the most extensively researched NP-complete problems in Computer Science. This thesis focuses on the design of feasible solvers for this problem. A SAT problem instance is a formula in propositional logic. A SAT solver attempts to find a solution for the formula. Our research focuses on a newer solver paradigm, hybrid solvers, where two solvers are combined in order to gain the benefits from both solvers in the search for a solution. Our hybrid solver, AmbSAT, combines two well-known solvers: the systematic Davis-Putnam-Logemann-Loveland solver (DPLL) and the stochastic WalkSAT solver. AmbSAT's design …

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Charateristics And Impact Of Interpersonal Conflicts On Requirements Risks, Avinder Walia Dec 2012

Charateristics And Impact Of Interpersonal Conflicts On Requirements Risks, Avinder Walia

Electronic Thesis and Dissertation Repository

Interpersonal conflicts in software projects have an impact on project’s success, product’s quality, team’s performance, etc. However, in Requirements Engineering (RE), there is dearth of research on this topic; previous research has focused largely on conflicts among requirements. We conducted a case study of an industrial project to determine the characteristics (e.g., type, severity, conflict management styles, etc.) and impact of interpersonal conflicts rooted in RE (RE-Conflicts), on project risks associated with requirements (e..g., inadequately identified requirements, incorrect requirements, etc). The findings show that the conflicts over administrative procedures (47%) had the highest frequency count. The highest number of …

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Investigation Of Low-Stress Silicon Nitride As A Replacement Material For Beryllium X-Ray Windows, David B. Brough Dec 2012

Investigation Of Low-Stress Silicon Nitride As A Replacement Material For Beryllium X-Ray Windows, David B. Brough

Theses and Dissertations

The material properties of low stress silicon nitride make it a possible replacement material for beryllium in X-ray windows. In this study, X-ray windows made of LPCVD deposited low stress silicon nitride are fabricated and characterized. The Young's modulus of the LPCVD low stress silicon nitride are characterized and found to be 226±23 GPa. The residual stress is characterized using two different methods and is found to be 127±25 MPa and 141±0.28 MPa. Two support structure geometries for the low stress silicon nitride X-ray windows are used. X-ray windows with thicknesses of 100 nm and 200 nm are suspended on …

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Rfid-Enabled Warehouse Process Optimization In The Tpl Industry, S. Wamba, A. Chatfield Dec 2012

Rfid-Enabled Warehouse Process Optimization In The Tpl Industry, S. Wamba, A. Chatfield

Dr Akemi Chatfield

Using the value chain model and a longitudinal real-world case study of a third-party logistics (TPL) supply chain, this study provides support for the enabling role of RFID technology in effecting warehouse process optimization. Furthermore, the findings of our study reveal the RFID technology implementation costs as the key inhibitors factor of RFID widespread adoption and usage among suppliers.

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