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Articles 1 - 30 of 43
Full-Text Articles in Engineering
Effect Of Coating Additives On The Rheological And Optical Properties Of Coated Papers, Burak Aksoy
Effect Of Coating Additives On The Rheological And Optical Properties Of Coated Papers, Burak Aksoy
Dissertations
Although additives are used in small amounts (below 2wt.% of the total solids) in a coating formulation, they play an important role in the runnability and end-use performance of the coating. Among coating additives, the use of insolubilizers and fluorescent whitening agents (FWA's) has increased due to theincrease in demand for higher quality graphic papers and packaging. Zirconium containing insolubilizers were studied for their rheological effects on silica ink jet coatings. Both zirconium species had an influence on the theological properties of the coating and its components. The interactions between thezirconium salts and the coating were found to be weak …
Fumed Metallic Oxides And Conventional Pigments For Glossy Inkjet Paper, Hyunkook Lee
Fumed Metallic Oxides And Conventional Pigments For Glossy Inkjet Paper, Hyunkook Lee
Dissertations
Product development activity in the area of inkjet printing papers has accelerated greatly to meet the rapidly growing market for inkjet papers. Advancements in inkjet printing technology have also placed new demands on the paper substrate due to faster printing rates, greater resolution through increased drop volumes, and colorants added to the ink. To meet these requirements, papermakers are turning to pigmented size press formulations or pigmented coating systems. For inkjet coating applications, both the internal porosity of the pigment particles as well as the packing porosity of the coating affect print quality and dry time. Pores between the pigment …
Modeling The Strategic Impact Of Management Accounting Methods On The Implementation Of Lean Manufacturing, David Joseph Meade
Modeling The Strategic Impact Of Management Accounting Methods On The Implementation Of Lean Manufacturing, David Joseph Meade
Dissertations
This study examines the impact from the adaptation of lean manufacturing strategies on key external financial performance measures as reported by a number of management accounting methods. The research is not concerned with creating a justification for lean manufacturing strategies but rather it evaluates the inadequacies of standard financial reporting methods to accurately reflect operational improvements possible in the key performance measures through the early stages of a lean program.
ProModel simulation software is used in conjunction with Microsoft Excel and Visual Basic to create a simulated repetitive manufacturing environment and production planning and control system. The study examines the …
Investigating Graphical User Interface Usability On Task Sequence And Display Structure Dependencies, Tirthankar Sengupta
Investigating Graphical User Interface Usability On Task Sequence And Display Structure Dependencies, Tirthankar Sengupta
Dissertations
Designing Graphical User Interfaces (GUI) requires the consideration of task sequence requirements (sequence of operations arising from task structures and application constraints) and display structure (layout of the elements of the interface) relationships. The basic purpose was to understand the usability differences of the interfaces through efficiency, motor performance, and search performance.
Thirty-two subjects performed experiments in four groups. The experiments differed in display structure and compatibility of task sequences. Subject mouse actions, mouse coordinates and eye positions were recorded. The derived measures, click efficiency, mouse traversal and eye visits to different areas of interest (namely the tool, object, and …
Network Anomaly Detection Using Management Information Base (Mib) Network Traffic Variables, Jun Li
Network Anomaly Detection Using Management Information Base (Mib) Network Traffic Variables, Jun Li
Dissertations
In this dissertation, a hierarchical, multi-tier, multiple-observation-window, network anomaly detection system (NADS) is introduced, namely, the MIB Anomaly Detection (MAD) system, which is capable of detecting and diagnosing network anomalies (including network faults and Denial of Service computer network attacks) proactively and adaptively. The MAD system utilizes statistical models and neural network classifier to detect network anomalies through monitoring the subtle changes of network traffic patterns. The process of measuring network traffic pattern is achieved by monitoring the Management Information Base (Mifi) II variables, supplied by the Simple Network Management Protocol (SNMP) LI. The MAD system then converted each monitored …
Modeling Contaminant Transport And Fate And Subsequent Impacts On Ecosystems, Ming Fan
Modeling Contaminant Transport And Fate And Subsequent Impacts On Ecosystems, Ming Fan
Dissertations
Assessing risks associated with the release of metals into the environment and managing remedial activities requires simulation tools that depict speciation and risk with accurate mechanistic models and well-defined transport parameters. Such tools need to address the following processes: (1) aqueous speciation, (2) distribution mechanisms, (3) transport, and (4) ecological risk. The primary objective of this research is to develop a simulation tool that accounts for these processes. Speciation in the aqueous phase can be assessed with geochemical equilibrium models, such as MINEQL+. Furthermore, metal distribution can be addressed mechanistically. Studies with Pb sorption to amorphous aluminum (HAG), iron (HFO), …
Continuity Of Bridges Composed Of Simple-Span Precast Prestressed Concrete Girders Made Continuous, Libin Yin
Continuity Of Bridges Composed Of Simple-Span Precast Prestressed Concrete Girders Made Continuous, Libin Yin
Dissertations
Bridges composed of simple-span, precast, prestressed concrete girders made continuous via cast-in-place decks and diaphragms are continuous only for live loads and superimposed dead loads. The continuity diaphragms often crack due to time dependent effects in the girders. These cracks not only impair bridge ascetics and durability, but also reduce "degree of continuity". A related issue is that joint construction is time consuming and expensive due to reinforcement congestion. This dissertation presents a series of field tests, analytical studies, and laboratory experiments concerning the design and performance of this type of bridge.
Based on a survey of the state departments …
Fluidization Of Nanoparticles, Caroline Hijung Nam
Fluidization Of Nanoparticles, Caroline Hijung Nam
Dissertations
During the past decade, nanoparticles (1-100 nm) and nanocomposites have become the focus of many studies due to the unique properties of nanostructured materials that make them attractive for various applications. Due to their atomic and molecular interactions, nanoparticles and nanocomposites have unique and often favorable catalytic, mechanical, optical, electronic and / or other properties. For instance, nanocrystalline copper is up to 5 times harder than conventional micron sized copper particles. Nanocomposites, such as a homogenous mixture of different nanoparticles, can also exhibit improved properties. Other examples include coating and reacting nanoparticles with a second nanostructured phase. These processes are …
Optimization Studies Of Thermal Bimorph Cantilevers, Electrostatic Torsion Actuators And Variable Capacitors, Wuyong Peng
Optimization Studies Of Thermal Bimorph Cantilevers, Electrostatic Torsion Actuators And Variable Capacitors, Wuyong Peng
Dissertations
In this dissertation, theoretical analyses and optimization studies are given for three kinds of MEMS devices: thermal bimorph cantilevers, electrostatic torsion actuators, and variable capacitors. Calculation, simulation, and experimental data are used to confirm the device behavior and demonstrate the application of the design approaches.
For thermal bimorph cantilevers, an analytical model is presented which allows theoretical analysis and quantitative optimization of the performance based on material properties and device dimensions. Bimorph cantilevers are divided into two categories for deflection optimization: either the total thickness is constant, or the cantilever has one constant and one variable layer thickness. The optimum …
Novel Internally-Staged Ultrafiltration For Protein Purification, Meredith Ann Feins
Novel Internally-Staged Ultrafiltration For Protein Purification, Meredith Ann Feins
Dissertations
A new ultrafiltration technique based on a multimembrane stack has been developed to fractionate proteins closer in molecular weight than conventionally possible. The technique is illustrated here by obtaining a pure protein product from a binary protein mixture. By employing membranes in series using the same membrane without any gaskets or spacers in-between, ultrafiltration is carried out to separate two proteins relatively close in molecular weight. Flat membranes, of the same molecular weight cutoff (MWCO) 30,000 or 100,000, are stacked together in the desired number, and ultrafiltration takes place. The membrane rejection of a protein is amplified with each additional …
Mechanisms Of Layer-Transfer Related To Silicon-On-Insulator Structures, Bo Chen
Mechanisms Of Layer-Transfer Related To Silicon-On-Insulator Structures, Bo Chen
Dissertations
The objective of this dissertation was to study the mechanisms that affect an efficient hydrogenation process in silicon and to validate a hypothesis concerning the hydrogenation mechanism of pre-implanted silicon wafers under hydrogen-plasma processing. These studies are related to a general process. A trapping layer for hydrogen was introduced by ion beam implantation into the silicon wafer. Next, this wafer was hydrogenated using a hydrogen plasma. It was hypothesized that the trapping layer acts as a getterer for the hydrogen diffusing into the silicon wafer. It was found that a large amount of hydrogen could be absorbed in the trapping …
Performance Evaluation Of Communication Systems With Transmit Diversity, Chunjun Gao
Performance Evaluation Of Communication Systems With Transmit Diversity, Chunjun Gao
Dissertations
Transmit diversity is a key technique to combat fading with multiple transmit antennae for next-generation wireless communication systems. Space-time block code (STBC) is a main component of this technique. This dissertation consists of four parts: the first three discuss performance evaluation of STBCs in various circumstances, the fourth outlines a novel differential scheme with full transmit diversity.
In the first part, closed-form expressions for the bit error rate (BER) are derived for STBC based on Alamouti's scheme and utilizing M-ary phase shift keying (MPSK) modulation. The analysis is carried out for a slow, flat Rayleigh fading channel with coherent detection …
The Design Of Adjustable Spherical Mechanisms Using Plane-To-Sphere And Sphere-To-Plane Projections, Wen-Tzong Lee
The Design Of Adjustable Spherical Mechanisms Using Plane-To-Sphere And Sphere-To-Plane Projections, Wen-Tzong Lee
Dissertations
The spherical mechanism is a particular type of spatial mechanism. Due to the orientation of its joint axes and the curvature of its links, the workspaces of spherical mechanisms (whether line segments, closed loops or area regions) are spherical in curvature. This characteristic of spherical mechanisms makes them quite effective and practical in motion path and function generation applications requiring spherical rigid body kinematics.
Although there are design methods available for spherical mechanisms, most of these methods do not consider the design of a single adjustable spherical mechanism. With an adjustable spherical mechanism, the user could for example, relocate the …
Development Of Dynamic Recursive Models For Freeway Travel Time Predictions, Xiaobo Liu
Development Of Dynamic Recursive Models For Freeway Travel Time Predictions, Xiaobo Liu
Dissertations
Traffic congestion has been a major problem in metropolitan areas, which is caused by either insufficient roadway capacity or unforesceable incidents. In order to promote the efficiency of the existing roadway networks and mitigate the impact of traffic congestion, the development of a sound prediction model for travel times is desirable.
A comprehensive literature review about existing prediction models was conducted by investigating the advantages, disadvantages, and limitations of each model. Based on the features and properties of previous models, the base models including exponential smoothing model (ESM), moving average model (MAM), and Kalman filtering model (KFM) are developed to …
Multi-Rate Access Schemes And Successive Interference Cancellation For Wireless Multimedia Mc-Cdma Communications, Mizhou Tan
Dissertations
To catch up with the fast changes of the information challenges, providing multimedia services has become a very important requirement for future wireless communications. A proper system, capable of supporting multi-rate transmissions as well as handling high quality of service (QoS) requirements in hostile wireless communication environments, should be sought. Multi-carrier CDMA (MC-CDMA), a combination of multi-carrier modulation (MCM) and direct-sequence CDMA (DS-CDMA), appears to be one of the most elegant solutions. In this dissertation, four multi-rate access schemes, termed uncoded fixed spreading length (UFSL), coded fixed spreading length (CFSL), multi-code fixed spreading length (MFSL) and variable spreading length (VSL), …
Boron And Phosphorous Implantation Into (100) Germanium : Modeling And Investigation Of Dopant Annealing Behavior, Yong Seok Suh
Boron And Phosphorous Implantation Into (100) Germanium : Modeling And Investigation Of Dopant Annealing Behavior, Yong Seok Suh
Dissertations
Germanium is increasingly being considered at this time for future silicon compatible optoelectronic and complementary metal oxide semiconductor (CMOS) device application. Germanium implantation will be a critical process for future device fabrication. However, critical properties like Pearson parameters and dopant activation temperatures are not well established. In this study, boron and phosphorus were implanted into (100) germanium with energies ranging from 20 to 320 keV and doses of 5 x 1013 to 5 x 1016 cm-2. The behavior of the boron and phosphorus before and after annealing for 3 hours at 400, 600 or 800°C in …
3-D Numerical Simulation Of Reactive Extrusion And Its Application To Polymerization Of Ε-Caprolactone In Co-Rotating Twin-Screw Extruders, Linjie Zhu
Dissertations
A 3-D numerical simulation model was proposed to predict the polymerization of ε-caprolactone in fully-filled conveying elements and kneading blocks of co-rotating twin-screw extruders, in which the kinetics equation for polymerization is coupled with continuity equation, momentum equation, and energy equation. With the 3-D model, parametric studies have been carried out to investigate the effects of screw configurations, screw diameter, operational conditions, values of heat from reaction, initiator concentration, and heat transfer conditions at barrel surface upon the polymerization progress. Two simulation models for the polymerization in the partially-filled channels were developed based on the conveying mechanisms of the reaction …
Providing Guaranteed Qos In The Hose-Modeled Vpn, Dong Wei
Providing Guaranteed Qos In The Hose-Modeled Vpn, Dong Wei
Dissertations
With the development of the Internet, Internet service providers (ISPs) are required to offer revenue-generating and value-added services instead of only providing bandwidth and access services. Virtual Private Network (VPN) is one of the most important value-added services for ISPs.
The "classical" VPN service is provided by implementing layer 2 technologies, either Frame Relay (FR) or Asynchronous Transfer Mode (ATM). With FR or ATM, virtual circuits are created before data delivery. Since the bandwidth and buffers are reserved, the QoS requirements can be naturally guaranteed. In the past few years, layer 3 VPN technologies are widely deployed due to the …
Phase Noise Effects On Ofdm : Analysis And Mitigation, Songping Wu
Phase Noise Effects On Ofdm : Analysis And Mitigation, Songping Wu
Dissertations
Orthogonal frequency division multiplexing (OFDM) is a promising technique which has high spectrum efficiency and the robustness against channel frequency selectivity. One drawback of OFDM is its sensitivity to phase noise. It has been shown that even small phase noise leads to significant performance loss of OFDM. Therefore, phase noise effects on OFDM systems need to be analyzed and methods be provided to its mitigation.
Motivated by what have been proposed in the literature, the exact signal to interference plus noise ratio (SINR) is derived in this dissertation for arbitrary phase noise levels. In a multiple access environment with multiple …
Enhancing Qos Provisioning And Granularity In Next Generation Internet, Jie Yang
Enhancing Qos Provisioning And Granularity In Next Generation Internet, Jie Yang
Dissertations
Next Generation IP technology has the potential to prevail, both in the access and in the core networks, as we are moving towards a multi-service, multimedia and high-speed networking environment. Many new applications, including the multimedia applications, have been developed and deployed, and demand Quality of Service (QoS) support from the Internet, in addition to the current best effort service. Therefore, QoS provisioning techniques in the Internet to guarantee some specific QoS parameters are more a requirement than a desire. Due to the large amount of data flows and bandwidth demand, as well as the various QoS requirements, scalability and …
Statistical Anomaly Denial Of Service And Reconnaissance Intrusion Detection, Zheng Zhang
Statistical Anomaly Denial Of Service And Reconnaissance Intrusion Detection, Zheng Zhang
Dissertations
This dissertation presents the architecture, methods and results of the Hierarchical Intrusion Detection Engine (HIDE) and the Reconnaissance Intrusion Detection System (RIDS); the former is denial-of-service (DoS) attack detector while the latter is a scan and probe (P&S) reconnaissance detector; both are statistical anomaly systems.
The HIDE is a packet-oriented, observation-window using, hierarchical, multi-tier, anomaly based network intrusion detection system, which monitors several network traffic parameters simultaneously, constructs a 64-bin probability density function (PDF) for each, statistically compares it to a reference PDF of normal behavior using a similarity metric, then combines the results into an anomaly status vector that …
Mobile Agent Based Distributed Network Management : Modeling, Methodologies And Applications, Jian Ye
Mobile Agent Based Distributed Network Management : Modeling, Methodologies And Applications, Jian Ye
Dissertations
The explosive growth of the Internet and the continued dramatic increase for all wireless services are fueling the demand for increased capacity, data rates, support of multimedia services, and support for different Quality of Services (QoS) requirements for different classes of services. Furthermore future communication networks will be strongly characterized by heterogeneity. In order to meet the objectives of instant adaptability to the users' requirements and of interoperability and seamless operation within the heterogeneous networking environments, flexibility in terms of network and resource management will be a key design issue. The new emerging technology of mobile agent (MA) has arisen …
Ad Hoc Network Security And Modeling With Stochastic Petri Nets, Congzhe Zhang
Ad Hoc Network Security And Modeling With Stochastic Petri Nets, Congzhe Zhang
Dissertations
Advances in wireless technology and portable computing along with demands for high user mobility have provided a major promotion toward the development of ad hoc networks. These networks feature dynamic topology, self-organization, limited bandwidth and battery power of a node. Unlike the existing commercial wireless systems and fixed infrastructure networks, they do not rely on specialized routers for path discovery and traffic routing. Security is an important issue in such networks. Typically, mobile nodes are significantly more susceptible to physical attacks than their wired counterparts.
This research intends to investigate the ad hoc network routing security by proposing a performance …
Qos Provisioning In Multimedia Streaming, Hong Zhao
Qos Provisioning In Multimedia Streaming, Hong Zhao
Dissertations
Multimedia consists of voice, video, and data. Sample applications include video conferencing, video on demand, distance learning, distributed games, and movies on demand. Providing Quality of Service (QoS) for multimedia streaming has been a difficult and challenging problem. When multimedia traffic is transported over a network, video traffic, though usually compressed/encoded for bandwidth reduction, still consumes most of the bandwidth. In addition, compressed video streams typically exhibit highly variable bit rates as well as long range dependence properties, thus exacerbating the challenge in meeting the stringent QoS requirements of multimedia streaming with high network utilization. Dynamic bandwidth allocation in which …
Ultra-Wideband Technology For Short-Range Wireless Communication, Li Zhao
Ultra-Wideband Technology For Short-Range Wireless Communication, Li Zhao
Dissertations
The ultra-wideband (UWB) radio core idea is to open large amounts of spectrum to a variety of users with little mutual interference between them. While ultra-wideband is being championed by several commercial companies, this technology has not followed the conventional path where commercial interest is preceded by years of academic research. This work attempts to fill in some of the gap by studying fundamental properties of communications with impulse-based radio UWB signals. We study jam resistance and capacity of UWB. Jam resistance is analyzed for binary pulse position modulation (PPM) with the interference being modeled as correlated Gaussian. Closed-form expressions …
Transmission And Detection For Space-Time Block Coding And V-Blast Systems, Lei He
Transmission And Detection For Space-Time Block Coding And V-Blast Systems, Lei He
Dissertations
This dissertation focuses on topics of data transmission and detection of space -time block codes (STBC). The STBCs can be divided into two main categories, namely, the orthogonal space-time block codes (OSTBC) and the quasi-orthogonal space-time codes (Q-OSTBC). The space-time block coded systems from transceiver design perspective for both narrow-band and frequency selective wireless environment are studied. The dissertation also processes and studies a fast iterative detection scheme for a high-rate space-time transmission system, the V-BLAST system.
In Chapter 2, a new OSTBC scheme with full-rate and full-diversity, which can be used on QPSK transceiver systems with four transmit antennas …
Hybrid Routing And Bridging Strategies For Large Scale Mobile Ad Hoc Networks, Sheng Xu
Hybrid Routing And Bridging Strategies For Large Scale Mobile Ad Hoc Networks, Sheng Xu
Dissertations
Multi-hop packet radio networks (or mobile ad-hoc networks) are an ideal technology to establish "instant" communication infrastructure for military and civilian applications in which both hosts and routers are mobile. In this dissertation, a position-based/link-state hybrid, proactive routing protocol (Position-guided Sliding-window Routing - PSR) that provides for a flat, mobile ad-hoc routing architecture is described, analyzed and evaluated. PSR is based on the superposition of link-state and position-based routing, and it employs a simplified way of localizing routing overhead, without having to resort to complex, multiple-tier routing organization schemes. A set of geographic routing zones is defined for each node, …
On The Dynamics And Kinetic Energy Of Axisymmetric And Wavy Taylor-Couette Flows, Javier M. Montefort
On The Dynamics And Kinetic Energy Of Axisymmetric And Wavy Taylor-Couette Flows, Javier M. Montefort
Dissertations
An experimental study of axisymmetric and wavy Taylor-Couette flows is presented in this research. The study is conducted to investigate the flowcharacteristics under steady state conditions in axisymmetric and wavy Taylor flows. Additionally, the time-dependent formation of axisymmetric vortices is also experimentally investigated. The radii and aspect ratios of the experimental facility utilized in this research are 0.672 and 20, respectively. The working fluid used during the experiments is water. The experiments were performed within the Taylor numbers range comprised by TC < T < 105 TC . A numerical scheme based on finite differences technique has been developed to validate …
A Conceptual Framework For Using Feedback Control Within Adaptive Traffic Control Systems, Renu Chhonkar
A Conceptual Framework For Using Feedback Control Within Adaptive Traffic Control Systems, Renu Chhonkar
Dissertations
Existing adaptive traffic control strategies lack an effective evaluation procedure to check the performance of the control plan after implementation. In the absence of an effective evaluation procedure, errors introduced in the system such as inaccurate estimates of arrival flows, are carried forward in time and reduce the efficiency of the traffic flow algorithms as they assess prevalent traffic conditions. It is evident that the feed-forward nature of these systems cannot accurately update the estimated quantities, especially during oversaturated conditions.
This research is an attempt to develop a conceptual framework for the application of feedback control within the basic operation …
Adaptive Learning For Event Modeling And Pattern Classification, Shuangshuang Dai
Adaptive Learning For Event Modeling And Pattern Classification, Shuangshuang Dai
Dissertations
It is crucial to detect, characterize and model events of interest in a new propulsion system. As technology advances, the amount of data being generated increases significantly with respect to time. This increase substantially strains our ability to interpret the data at an equivalent rate. It demands efficient methodologies and algorithms in the development of automated event modeling and pattern recognition to detect and characterize events of interest and correlate them to the system performance. The fact that the information required to properly evaluate system performance and health is seldom known in advance further exacerbates this issue.
Event modeling and …