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- Title
- Non-linear convection of a vortex sheet past a cascade of airfoils.
- Creator
- van den Berg, Stanislas Franck., Florida Atlantic University, Glegg, Stewart A. L.
- Abstract/Description
-
The interaction of rotor turbulence with the stator is currently believed to be the predominant mechanism of noise radiation from turbofans in aircraft engines. This thesis presents a general method to compute unsteady 2-D potential flows past a cascade of airfoils. The procedure uses source and vortex distributions on the surface of the airfoils, creation of wakes downstream of the airfoils and non-linear convection of the perturbed flow. These features are designed to satisfy a condition of...
Show moreThe interaction of rotor turbulence with the stator is currently believed to be the predominant mechanism of noise radiation from turbofans in aircraft engines. This thesis presents a general method to compute unsteady 2-D potential flows past a cascade of airfoils. The procedure uses source and vortex distributions on the surface of the airfoils, creation of wakes downstream of the airfoils and non-linear convection of the perturbed flow. These features are designed to satisfy a condition of no-flow through the surface of the airfoils and the Kutta condition at the trailing edge of each of these airfoils. The investigation proves the importance of applying the Kutta condition. It was also shown that an infinite cascade is well approximated by a small number of airfoils and that the non-linear rather than linear convection of vorticity has a large effect on the spectrum of the unsteady lift of an airfoil.
Show less - Date Issued
- 1998
- PURL
- http://purl.flvc.org/fcla/dt/15586
- Subject Headings
- Vortex-motion, Cascades (Fluid dynamics), Unsteady flow (Fluid dynamics)
- Format
- Document (PDF)
- Title
- Predicting decay in program modules of legacy software systems.
- Creator
- Joshi, Dhaval Kunvarabhai., Florida Atlantic University, Khoshgoftaar, Taghi M.
- Abstract/Description
-
Legacy software systems may go through many releases. It is important to ensure that the reliability of a system improves with subsequent releases. Methods are needed to identify decaying software modules, i.e., modules for which quality decreases with each system release. Early identification of such modules during the software life cycle allows us to focus quality improvement efforts in a more productive manner, by reducing resources wasted for testing and improving the entire system. We...
Show moreLegacy software systems may go through many releases. It is important to ensure that the reliability of a system improves with subsequent releases. Methods are needed to identify decaying software modules, i.e., modules for which quality decreases with each system release. Early identification of such modules during the software life cycle allows us to focus quality improvement efforts in a more productive manner, by reducing resources wasted for testing and improving the entire system. We present a scheme to classify modules in three groups---Decayed, Improved, and Unchanged---based on a three-group software quality classification method. This scheme is applied to three different case studies, using a case-based reasoning three-group classification model. The model identifies decayed modules, and is validated over different releases. The main goal of this work is to focus on the evolution of program modules of a legacy software system to identify modules that are difficult to maintain and may need to be reengineered.
Show less - Date Issued
- 2002
- PURL
- http://purl.flvc.org/fcla/dt/12899
- Subject Headings
- Software reengineering, Computer software--Quality control, Software measurement, Software maintenance
- Format
- Document (PDF)
- Title
- Prediction of broadband self-noise of an airfoil.
- Creator
- Gomez, Carlos L., Florida Atlantic University, Glegg, Stewart A. L.
- Abstract/Description
-
With the increase of air traffic and the introduction of larger aircraft and therefore larger engines, the noise generated by aircraft engines have become of greater importance. In order to address these problems, noise prediction codes must be developed in order to better understand the noise generating process. This thesis addresses important issues related to broadband self-noise from ducted fans based on the prediction model developed by Glegg and Jochault [1]. By addressing issues...
Show moreWith the increase of air traffic and the introduction of larger aircraft and therefore larger engines, the noise generated by aircraft engines have become of greater importance. In order to address these problems, noise prediction codes must be developed in order to better understand the noise generating process. This thesis addresses important issues related to broadband self-noise from ducted fans based on the prediction model developed by Glegg and Jochault [1]. By addressing issues regarding the prediction of broadband self-noise from an isolated airfoil with the observer in the far field directly overhead (at 90° above), improvements can be made to Glegg and Jochault's approach for ducted fans. The prediction of broadband self-noise at 90° above a single airfoil is done by considering boundary layer parameters, the results obtained are compared with theoretical approaches, as well as experimental results obtained by Brooks [2] in order to verify its accuracy.
Show less - Date Issued
- 2006
- PURL
- http://purl.flvc.org/fcla/dt/13377
- Subject Headings
- Aerofoils--Noise, Noise control, Blades--Noise, Rotors--Noise, Acoustical engineering--Mathematical models, Acoustic models
- Format
- Document (PDF)
- Title
- Power flow analysis of a structure subjected to distributed excitation.
- Creator
- Cimerman, Benjamin Pierre., Florida Atlantic University, Cuschieri, Joseph M.
- Abstract/Description
-
An analytical investigation based on the Power Flow Method is presented for the prediction of vibrational Power Flow in simple connected structures subjected to various forms of distributed excitations. The principle of the power flow method consists of dividing the global structure into a series of substructures which can be analyzed independently and then coupled through the boundary conditions. Power flow expressions are derived for an L-shaped plate structure, subjected to any form of...
Show moreAn analytical investigation based on the Power Flow Method is presented for the prediction of vibrational Power Flow in simple connected structures subjected to various forms of distributed excitations. The principle of the power flow method consists of dividing the global structure into a series of substructures which can be analyzed independently and then coupled through the boundary conditions. Power flow expressions are derived for an L-shaped plate structure, subjected to any form of distributed mechanical excitation or excited by an acoustic plane wave. In the latter case air loading is considered to have a significant effect on the power input to the structure. Fluid-structure interaction considerations lead to the derivation of a corrected mode shape for the normal velocity, and the determination of the scattered pressure components in the expressions for the Power Flow.
Show less - Date Issued
- 1990
- PURL
- http://purl.flvc.org/fcla/dt/14578
- Subject Headings
- Structural dynamics, Plates (Engineering)--Vibration
- Format
- Document (PDF)
- Title
- Potential attenuation and anode current output determination alternatives for galvanic anode cathodic protection upon offshore pipelines.
- Creator
- Bethune, Keith P., Florida Atlantic University, Hartt, William H.
- Abstract/Description
-
A recently developed equation governing cathodic polarization attenuation along a pipeline protected by galvanic anodes is first solved. The solution is based upon a numerical finite difference method (FDM). The resulting subroutine computes the polarization along the cathode and the corresponding anode current output based upon the physical design variables and electrochemical properties of the cathode. Validation of this method is accomplished through comparisons with a proven existing...
Show moreA recently developed equation governing cathodic polarization attenuation along a pipeline protected by galvanic anodes is first solved. The solution is based upon a numerical finite difference method (FDM). The resulting subroutine computes the polarization along the cathode and the corresponding anode current output based upon the physical design variables and electrochemical properties of the cathode. Validation of this method is accomplished through comparisons with a proven existing method for attenuation prediction, namely the Boundary Element Method (BEM). As both the FDM and BEM solutions are mathematically complex and time consuming, it is then demonstrated that a modified form of Ohm's Law that quantitatively interrelates (1) design life, (2) anode size, weight, and properties, (3) pipe size, current demand, and coating quality, (4) sea water resistivity, (5) magnitude of polarization, and (6) anode spacing is sufficient for design purposes where metallic resistance of the pipeline itself is negligible. This new method can be easily adapted in a spreadsheet type analysis as no numerical subroutine is necessary. One size pipeline of varying lengths is analyzed using these methods for comparisons and validation and the effect of metallic resistance on attenuation profiles is examined. It is concluded that for small diameter pipelines with anode spacing up to 800 m metallic resistance is negligible, and thus all three methods can be used with reasonable confidence for spacings below 800 m. An analysis to illustrate the effect of a stratified electrolyte in the vicinity of the pipeline has been initiated and preliminary results are also presented.
Show less - Date Issued
- 2000
- PURL
- http://purl.flvc.org/fcla/dt/12672
- Subject Headings
- Underwater pipelines, Pipelines--Cathodic protection
- Format
- Document (PDF)
- Title
- ROBOT CALIBRATION USING STEREO VISION.
- Creator
- CHEN, SHOUPU., Florida Atlantic University, Roth, Zvi S., Sudhakar, Raghavan
- Abstract/Description
-
This thesis deals with a study of using the stereo vision technique in the robot calibration. Three cameras are used in measurement to extract the position information of a target point attached onto each of the robot manipulator links for the purpose of identifying the actual kinematic parameters of every link of the robot manipulator under testing. The robot kinematic model used in this study is the S-Model which is an extension of the well-known Denavit-Hartenberg model. The calibration...
Show moreThis thesis deals with a study of using the stereo vision technique in the robot calibration. Three cameras are used in measurement to extract the position information of a target point attached onto each of the robot manipulator links for the purpose of identifying the actual kinematic parameters of every link of the robot manipulator under testing. The robot kinematic model used in this study is the S-Model which is an extension of the well-known Denavit-Hartenberg model. The calibration has been done on the wrist of the IBM 7565 robot. The experiment set-up and results and the necessary software are all presented in this thesis.
Show less - Date Issued
- 1987
- PURL
- http://purl.flvc.org/fcla/dt/14416
- Subject Headings
- Robotics--Calibration--Measurement
- Format
- Document (PDF)
- Title
- Radius distribution of ocean near surface bubbles.
- Creator
- Auffret, Yvan., Florida Atlantic University, Glegg, Stewart A. L.
- Abstract/Description
-
This study proposed to determine an ocean surface bubble radius distribution using theoretical noise models, experimental noise spectral data and a theoretical model for the bubble size distribution. The obtained distribution was compared to previous experimental distributions. A good agreement was found for the radius upper cut-off but the shape and the peak radius of the distribution are different from experimental observations. The most probable reasons for these differences were given....
Show moreThis study proposed to determine an ocean surface bubble radius distribution using theoretical noise models, experimental noise spectral data and a theoretical model for the bubble size distribution. The obtained distribution was compared to previous experimental distributions. A good agreement was found for the radius upper cut-off but the shape and the peak radius of the distribution are different from experimental observations. The most probable reasons for these differences were given. Moreover, the validity of recent theoretical bubble noise models was checked. Eventually, the main limitations of the study were pointed out and directions for future works were given.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/14922
- Subject Headings
- Underwater acoustics, Acoustic surface waves, Bubbles
- Format
- Document (PDF)
- Title
- Radar detection techniques: Application of stochastical and fractal strategies.
- Creator
- De Groff, Dolores F., Florida Atlantic University, Neelakanta, Perambur S.
- Abstract/Description
-
This thesis is concerned with the evaluation of radar detection performance specific to the following target and background considerations: (1) Stochastical description and determination of the envelope statistics pertaining to radar clutter of the coastline regions. (2) Detection of low-altitude targets by sea-borne radars operating near the coastline; and (3) Fractal characterization of the ocean surface as viewed by a satellite-based radar altimeter. The first problem refers to the...
Show moreThis thesis is concerned with the evaluation of radar detection performance specific to the following target and background considerations: (1) Stochastical description and determination of the envelope statistics pertaining to radar clutter of the coastline regions. (2) Detection of low-altitude targets by sea-borne radars operating near the coastline; and (3) Fractal characterization of the ocean surface as viewed by a satellite-based radar altimeter. The first problem refers to the elucidation of the most appropriate statistics that would describe the relevant envelope distribution of the clutter caused by the dual region of sea and land of a typical coastline environment. In the second analysis, performance of the radar in terms of false-alarm and detection probabilities is predicted. The third effort addressed provides a fractal description of the ocean surface as viewed by a satellite based radar altimeter. By characterizing the ocean bed as a fractal surface, the extent to which the sea surface data contributes errors to the mispointing/autoboresight information is ascertained.
Show less - Date Issued
- 1990
- PURL
- http://purl.flvc.org/fcla/dt/14651
- Subject Headings
- Radar--Interference, Radar
- Format
- Document (PDF)
- Title
- Realization and implementation of separable-in-denominator two-dimensional digital filter.
- Creator
- Huang, Ziqiang., Florida Atlantic University, Zilouchian, Ali
- Abstract/Description
-
In this thesis, a partial fraction expansion of a separable-in-denominator 2-D transfer function is given. Based on this expansion, several novel realizations of separable-in-denominator 2-D filter are provide. These realizations have the properties of highly parallel structure and improved throughput delay. The performance figures are given in the tables. A method of evaluation of quantization error of separable-in-denominator 2-D filter is also derived by using the residue method. Formulas...
Show moreIn this thesis, a partial fraction expansion of a separable-in-denominator 2-D transfer function is given. Based on this expansion, several novel realizations of separable-in-denominator 2-D filter are provide. These realizations have the properties of highly parallel structure and improved throughput delay. The performance figures are given in the tables. A method of evaluation of quantization error of separable-in-denominator 2-D filter is also derived by using the residue method. Formulas for calculation of roundoff noise of proposed structures are provided. Two programs which can be used to calculate the roundoff noise of proposed structure are listed in the Appendix. To run the programs, we need only to input the constant coefficients of expanded transfer function. At last, an optimal block realization of separable-in-denominator 2-D filter is discussed and the criterion for the absence of limit cycles for a second-order 2-D block is given.
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/14879
- Subject Headings
- Real-time data processing, Image processing--Digital techniques, Electric filters, Digital--Computer programs
- Format
- Document (PDF)
- Title
- Real time method for remote measurement of compressional wave attenuation.
- Creator
- DeBruin, Darryl L., Florida Atlantic University, Schock, Steven G.
- Abstract/Description
-
An acoustic measurement system is developed to estimate the compressional wave attenuation of marine sediments in real time. A chirp sonar transmits filtered digital reflection data to a signal processing computer that processes the data on an AT&T DSP32C chip. The signal processing computer estimates and displays the center frequency of the processed pulse as it is attenuated by the ocean sediments. Wavelet modelling establishes the relationship between the center frequency shift and...
Show moreAn acoustic measurement system is developed to estimate the compressional wave attenuation of marine sediments in real time. A chirp sonar transmits filtered digital reflection data to a signal processing computer that processes the data on an AT&T DSP32C chip. The signal processing computer estimates and displays the center frequency of the processed pulse as it is attenuated by the ocean sediments. Wavelet modelling establishes the relationship between the center frequency shift and relaxation time, from which the sediment type and compressional wave attenuation are determined. Frequency contours from two different data sites demonstrate that the system is able to reliably estimate sediment type and compressional wave attenuation. Error introduced by noise is below 1% for noise levels less than 0.1 of the normalized processed signal. Random error in the estimates is minimized by determining reliable frequency values and by ensemble averaging the values.
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/14824
- Subject Headings
- Marine sediments--Acoustic properties, Signal processing--Computer simulation
- Format
- Document (PDF)
- Title
- Remote labs: Design and implementation issues.
- Creator
- Aoudi, Samer M., Florida Atlantic University, Alhalabi, Bassem A.
- Abstract/Description
-
This thesis proposes the use of remote laboratory experiments in distance education as a tool to add a reality factor to the distance learning process, thus combining the convenience of distance education with the effectiveness of the traditional physical campus, through its laboratories and technological resources. Moreover, this research studies the different aspects of distance education and remote labs and then provides a proposition to develop an effective remote laboratory setup....
Show moreThis thesis proposes the use of remote laboratory experiments in distance education as a tool to add a reality factor to the distance learning process, thus combining the convenience of distance education with the effectiveness of the traditional physical campus, through its laboratories and technological resources. Moreover, this research studies the different aspects of distance education and remote labs and then provides a proposition to develop an effective remote laboratory setup. Furthermore, it introduces and discusses the different components of a general remote lab experiment and applies the proposed process to an actual remote lab experiment, namely 'The Characteristics of a Resistor'. Remote labs is an invention of creativity in the world of distance education. This thesis is based on the pioneering work of Dr. Alhalabi and Dr. Hamza.
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/12737
- Subject Headings
- Distance education, Internet in education, Java (Computer program language)
- Format
- Document (PDF)
- Title
- Remote laboratories for distance education.
- Creator
- Anandapuram, Sudeep Hari., Florida Atlantic University, Alhalabi, Bassem A.
- Abstract/Description
-
In the past few years many US institutions of higher education have established virtual classrooms where learners pursue higher education via the Internet. The true challenge in Distance Education however remains; how do students perform real lab experiments--such as electronics over the Internet? To examine this challenge, a survey was conducted on over fifty Web-based educational environments, to assess the shortcomings of laboratory facilities currently available on the Internet. The...
Show moreIn the past few years many US institutions of higher education have established virtual classrooms where learners pursue higher education via the Internet. The true challenge in Distance Education however remains; how do students perform real lab experiments--such as electronics over the Internet? To examine this challenge, a survey was conducted on over fifty Web-based educational environments, to assess the shortcomings of laboratory facilities currently available on the Internet. The survey revealed that contemporary labs touted to be virtual environments are merely software simulations. Hence the new idea of a facility that will realistically provide lab experiments over the Internet. With this aim, an innovative system is designed using object-oriented methodologies in Unified Modeling Language to include all aspects of software and hardware. Java/RMI is used as the system's development tool. An experiment to measure the "VI characteristics of a Resistor" is built using National Instruments' DAQ systems. The students can logon through the Internet, register, and perform experiments by sending various current values, and measure the corresponding voltages across a resistor. The results are submitted for grade and the teaching assistant can grade the student after observing the input and output values over the Internet.
Show less - Date Issued
- 1999
- PURL
- http://purl.flvc.org/fcla/dt/15636
- Subject Headings
- Distance education, Virtual reality
- Format
- Document (PDF)
- Title
- Remote labs: Active element IV characteristics.
- Creator
- Abu-El Humos, Ali M., Florida Atlantic University, Alhalabi, Bassem A.
- Abstract/Description
-
This thesis proposes the use of remote laboratory experiments in distance education. Remote labs combine both the convenience of distance education and the effectiveness of the traditional physical campus labs. Moreover, this research studies the different hardware and software technologies that would make remote lab experimentation feasible in terms of cost and quality. The focus in this thesis is how to use BS2 with Microsoft ASP and COM technologies to build a remote lab experiment with...
Show moreThis thesis proposes the use of remote laboratory experiments in distance education. Remote labs combine both the convenience of distance education and the effectiveness of the traditional physical campus labs. Moreover, this research studies the different hardware and software technologies that would make remote lab experimentation feasible in terms of cost and quality. The focus in this thesis is how to use BS2 with Microsoft ASP and COM technologies to build a remote lab experiment with minimum hardware and software cost, while maintaining satisfactory on-line experiment quality. Remote labs is a creative innovation in the world of distance education. This thesis is based on the pioneering work of Dr. Alhalabi and Dr. Hamza.
Show less - Date Issued
- 2002
- PURL
- http://purl.flvc.org/fcla/dt/12939
- Subject Headings
- Distance education, Internet in higher education, Scientific apparatus and instruments--Computer simulation
- Format
- Document (PDF)
- Title
- A STUDY OF FRICTION DAMPING AS APPLIED TO VIBRATING STRUCTURES.
- Creator
- DESAI, VIJAY R., Florida Atlantic University, Cuschieri, Joseph M.
- Abstract/Description
-
Of the many methods of introducing damping in vibrating structures, the dissipation of energy due to interfacial slip can significantly increase the damping loss factor. However, because of the lack of understanding and other phenomena such as fretting corrosion and loss of structural rigidity, friction damping is rarely used. A study was thus undertaken to investigate this complex phenomenon, with emphasis on trying to gain a better understanding of friction damping with certain parameters...
Show moreOf the many methods of introducing damping in vibrating structures, the dissipation of energy due to interfacial slip can significantly increase the damping loss factor. However, because of the lack of understanding and other phenomena such as fretting corrosion and loss of structural rigidity, friction damping is rarely used. A study was thus undertaken to investigate this complex phenomenon, with emphasis on trying to gain a better understanding of friction damping with certain parameters such as clamping pressure, frequency, magnitude of excitation and surface finish. Although the non-linearities associated with friction makes this mechanism difficult to model mathematically, finite element (FE) analysis shows some promise. Although the results obtained using an FE model were not exactly comparable to the experimental results, these analytical results did show the same general trends as observed in the experiments.
Show less - Date Issued
- 1987
- PURL
- http://purl.flvc.org/fcla/dt/14369
- Subject Headings
- Damping (Mechanics), Vibration
- Format
- Document (PDF)
- Title
- A STUDY OF STRESS CORROSION CRACKING IN 7079-T651 ALUMINUM.
- Creator
- FINNEGAN, JOHN EDMUND., Florida Atlantic University, Hartt, William H.
- Abstract/Description
-
This study investigated the stress corrosion cracking behavior of aluminum alloy 7079 - T651 in two corrosive environments, sea water and a 3% NaCl-distilled water solution. Self stressing, double cantilever beam specimens were employed; and these were stressed at various levels, exposed in one of the two test environments and crack extension monitored as a function of time. Equations for the plane strain stress intensity factor (K1) were compared and evaluated, with respect to stress...
Show moreThis study investigated the stress corrosion cracking behavior of aluminum alloy 7079 - T651 in two corrosive environments, sea water and a 3% NaCl-distilled water solution. Self stressing, double cantilever beam specimens were employed; and these were stressed at various levels, exposed in one of the two test environments and crack extension monitored as a function of time. Equations for the plane strain stress intensity factor (K1) were compared and evaluated, with respect to stress intensities calculated from compliance measurements. Results suggest that stress intensity is not the only important variable controlling crack growth rate and a time dependent cracking mechanism may govern a portion of crack growth.
Show less - Date Issued
- 1975
- PURL
- http://purl.flvc.org/fcla/dt/13730
- Subject Headings
- Aluminum--Corrosion, Stress corrosion
- Format
- Document (PDF)
- Title
- Sediment classification of the sea floor using the Chirp Sonar and the Biot model.
- Creator
- Beaujean, Pierre-Philippe, Florida Atlantic University, LeBlanc, Lester R.
- Abstract/Description
-
A new method is proposed to infer the geotechnical properties of the sea floor from its response to the frequency-modulated pulses emitted by the subbottom profiler called Chirp Sonar. The environment is assumed to be a multilayered medium, composed of homogeneous layers, or an inhomogeneous half-space with depth-dependent properties. The acoustic response of the sediment is computed using the Biot-Stoll theory. The Levenberg-Marquardt method is applied to fit the synthetic response to the...
Show moreA new method is proposed to infer the geotechnical properties of the sea floor from its response to the frequency-modulated pulses emitted by the subbottom profiler called Chirp Sonar. The environment is assumed to be a multilayered medium, composed of homogeneous layers, or an inhomogeneous half-space with depth-dependent properties. The acoustic response of the sediment is computed using the Biot-Stoll theory. The Levenberg-Marquardt method is applied to fit the synthetic response to the experimental response of an homogeneous layer overlying the sea floor. The porosity, the permeability, the mean grain diameter, the mass density, the bulk modulus and the shear modulus within this sediment layer can be estimated. A multilayered medium with depth-dependent properties could be applied to this inversion technique in the future.
Show less - Date Issued
- 1995
- PURL
- http://purl.flvc.org/fcla/dt/15208
- Subject Headings
- Marine sediments--Acoustic properties, Underwater acoustics--Measurement, Ocean bottom, Sonar
- Format
- Document (PDF)
- Title
- Sediment layer tracking using neural networks.
- Creator
- Freyermuth, Vincent Nicolas., Florida Atlantic University, Schock, Steven G.
- Abstract/Description
-
The detection of sediment layer interfaces in normal incidence acoustic reflection data is a requirement for automatic classification and geologic mapping of subsurface layers. The detection is difficult because of the constructive and destructive interference caused by the impedance changes in the sediment column and high scattering noise levels. The purpose of this work is to implement a procedure using neural networks that automatically detects the sediment layers from the envelope of...
Show moreThe detection of sediment layer interfaces in normal incidence acoustic reflection data is a requirement for automatic classification and geologic mapping of subsurface layers. The detection is difficult because of the constructive and destructive interference caused by the impedance changes in the sediment column and high scattering noise levels. The purpose of this work is to implement a procedure using neural networks that automatically detects the sediment layers from the envelope of acoustic reflections. The data was collected using a sub-bottom profiler that transmits a 2 to 10 kHz FM pulse. The detection procedure is a three step method: a first neural network removes most of the reflections due to random scatterers, a second neural network tracks the layers and a third algorithm recognizes the segments of detected layers corresponding to the same sediment interface Applied on different sub-bottom images, the procedure detects more than 80% of the layers correctly.
Show less - Date Issued
- 1998
- PURL
- http://purl.flvc.org/fcla/dt/15561
- Subject Headings
- Neural networks (Computer science), Marine sediments--Acoustic properties
- Format
- Document (PDF)
- Title
- RESPONSE OF 1018 STEEL TO CONCURRENT CYCLIC LOADING AND CATHODIC POLARIZATION IN NATURAL SEA WATER.
- Creator
- HOOPER, WILLIAM CLARENCE., Florida Atlantic University, Hartt, William H.
- Abstract/Description
-
Reverse bend, constant deflection fatigue experiments were conducted in natural sea water at 1850 cycles per minute (cpm) to investigate the response of 1018 notched steel to concurrent cyclic loading and cathodic polarization. For comparison purposes S-log N curves were also determined in air and high purity argon. These indicate that the endurance limit established in sea water by cathodic polarization at -0.85 volts, Saturated Calomel Electrode (SCE), is greater than in either air or argon...
Show moreReverse bend, constant deflection fatigue experiments were conducted in natural sea water at 1850 cycles per minute (cpm) to investigate the response of 1018 notched steel to concurrent cyclic loading and cathodic polarization. For comparison purposes S-log N curves were also determined in air and high purity argon. These indicate that the endurance limit established in sea water by cathodic polarization at -0.85 volts, Saturated Calomel Electrode (SCE), is greater than in either air or argon. Two mechanisms are considered as responsible for this behavior. 1. Presence of carbonate and hydroxide deposits coupled with increased alkalinity at non-propagating crack tips. 2. Adsorbed OH- layer at non-propagating crack tips.
Show less - Date Issued
- 1976
- PURL
- http://purl.flvc.org/fcla/dt/13781
- Subject Headings
- Steel--Testing
- Format
- Document (PDF)
- Title
- STUDY OF BANDWIDTH ALLOCATION STRATEGIES FOR NETWORKS INTEGRATING VOICE AND DATA.
- Creator
- IZQUIERDO, MICHAEL ROBERT., Florida Atlantic University, Ilyas, Mohammad
- Abstract/Description
-
The purpose of this thesis is to study three types of bandwidth allocation strategies for a network integrating voice and data, commonly referred to as Integrated Services Digital Network or ISDN, using GPSS V simulati ons. The strategies are Non-Boundary, Movable-Boundary, and Non- and Movable- Boundary with Digital Speech Interpolation. The theoretical behavior of each strategy is discussed. Exact solutions for small systems with one or two slots is shown along with approximations for...
Show moreThe purpose of this thesis is to study three types of bandwidth allocation strategies for a network integrating voice and data, commonly referred to as Integrated Services Digital Network or ISDN, using GPSS V simulati ons. The strategies are Non-Boundary, Movable-Boundary, and Non- and Movable- Boundary with Digital Speech Interpolation. The theoretical behavior of each strategy is discussed. Exact solutions for small systems with one or two slots is shown along with approximations for larger systems. General descriptions of the GPSS models for each strategy is provided. The GPSS model source code for each strategy is presented in the Appendix. Simulation is used to explore the effects of the service time ratio a of voice and data on system performance. Also, the performance of Time Division Multiplex or TDM systems with 24 channels, commonly referred to as Tl, is shown.
Show less - Date Issued
- 1987
- PURL
- http://purl.flvc.org/fcla/dt/14355
- Subject Headings
- Integrated services digital networks, Time management
- Format
- Document (PDF)
- Title
- Reputation-based system for encouraging cooperation of nodes in mobile ad hoc networks.
- Creator
- Anantvalee, Tiranuch., Florida Atlantic University, Wu, Jie
- Abstract/Description
-
In a mobile ad hoc network, node cooperation in packet forwarding is required for the network to function properly. However, since nodes in this network usually have limited resources, some selfish nodes might intend not to forward packets to save resources for their own use. To discourage such behavior, we propose RMS, a reputation-based system, to detect selfish nodes and respond to them by showing that being cooperative will benefit there more than being selfish. We also detect, to some...
Show moreIn a mobile ad hoc network, node cooperation in packet forwarding is required for the network to function properly. However, since nodes in this network usually have limited resources, some selfish nodes might intend not to forward packets to save resources for their own use. To discourage such behavior, we propose RMS, a reputation-based system, to detect selfish nodes and respond to them by showing that being cooperative will benefit there more than being selfish. We also detect, to some degree, nodes who forward only the necessary amount of packets to avoid being detected as selfish. We introduce the use of a state model to decide what we should do or respond to nodes in each state. In addition, we introduce the use of a timing period to control when the reputation should be updated and to use as a timeout for each state. The simulation results show that RMS can identify selfish nodes and punish them accordingly, which provide selfish nodes with an incentive to behave more cooperatively.
Show less - Date Issued
- 2006
- PURL
- http://purl.flvc.org/fcla/dt/13406
- Subject Headings
- Computer networks--Security measures, Wireless communication systems, Routers (Computer networks), Computer network architectures
- Format
- Document (PDF)