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Title: IMPACT BEHAVIOR OF CONCRETE BEAMS WITH CORRODING REINFORCING STEEL.
Creator: DESNOYERS, JEAN-FRANCOIS., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: This thesis presents an analytical and experimental investigation of the remaining impact strength of concrete beams with corroding reinforcement. Concrete beams were subjected to impact using a centrally loaded instrumented dropweight system. Three different amounts of steel corrosion were used to simulate ten, twenty, and thirty years of seawater exposure. The first part in the analytical investigation involved the use of the finite element code ADINA. The second included development of...
Show moreThis thesis presents an analytical and experimental investigation of the remaining impact strength of concrete beams with corroding reinforcement. Concrete beams were subjected to impact using a centrally loaded instrumented dropweight system. Three different amounts of steel corrosion were used to simulate ten, twenty, and thirty years of seawater exposure. The first part in the analytical investigation involved the use of the finite element code ADINA. The second included development of three physical models; the first based on a beam impact equation of forced vibration for a pin-ended beam with center span impact, the second a two-degree-of-freedom model, and the third a three-degree-of-freedom model taking into account the stiffness of the supports for the impacted beam specimens. The different analytical results showed good correlation with the test values of the impact energies. Also, the energy values for the different corrosion periods obtained from the ADINA analysis compared well with experimental ones.
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Date Issued: 1987
PURL: http://purl.flvc.org/fcla/dt/14371
Subject Headings: Concrete beams, Metals--Impact testing
Format: Document (PDF)

Title: INFLUENCE OF SELECTED ADMIXTURES UPON CONCRETE CRACKING DUE TO EMBEDDED METAL CORROSION.
Creator: YAU, SHI-SHEN, Florida Atlantic University
Abstract/Description: The influence of selected iron chelating agents upon corrosion and cracking of steel reinforced concrete has been investigated. Five chelating agents including EDTA, DTPA, TEA, HEDTA and Chel-138 were used. The experiments involved determination of (1) the influence of iron chelating agents on iron solubility limit, (2) the effect of admixtures upon compressive strength of concrete, (3) the influence of chelating admixtures upon steel corrosion and (4) cracking resistance of concrete...
Show moreThe influence of selected iron chelating agents upon corrosion and cracking of steel reinforced concrete has been investigated. Five chelating agents including EDTA, DTPA, TEA, HEDTA and Chel-138 were used. The experiments involved determination of (1) the influence of iron chelating agents on iron solubility limit, (2) the effect of admixtures upon compressive strength of concrete, (3) the influence of chelating admixtures upon steel corrosion and (4) cracking resistance of concrete specimens with and without selected iron chelating agents. Results from test groups (1) and (3) were encouraging; however, compressive strength of concrete specimens with admixtures was less than for specimens with no admixture. In addition, specimens with chelating admixtures had approximately 5.5 to 82 percent shorter cracking time than for the no admixture ones. Explanations for this are presented, and certain conclusions are reached regarding the usefulness of a chelating admixture for mitigating concrete cracking.
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Date Issued: 1978
PURL: http://purl.flvc.org/fcla/dt/13952
Subject Headings: Concrete Coatings--Testing, Ocean Engineering
Format: Document (PDF)

Title: INFLUENCE OF DISSOLVED ORGANICS IN SEA WATER ON THE CORROSION BEHAVIOR OF SELECTED METALS.
Creator: MACDOWELL, LOUIS GARDNER, III, Florida Atlantic University
Abstract/Description: Corrosion experiments have been performed upon steel and copper in natural sea water, photo-oxidized sea water and 3.5% sodium chloride-distilled water solutions. Anodic and cathodic polarization scans were conducted, and the resulting curves were employed to characterize corrosion behavior in each of the electrolytes. While little difference as a function of electrolyte was noted for tests upon copper, variations were apparent in the case of steel. The effect of environment has been...
Show moreCorrosion experiments have been performed upon steel and copper in natural sea water, photo-oxidized sea water and 3.5% sodium chloride-distilled water solutions. Anodic and cathodic polarization scans were conducted, and the resulting curves were employed to characterize corrosion behavior in each of the electrolytes. While little difference as a function of electrolyte was noted for tests upon copper, variations were apparent in the case of steel. The effect of environment has been interpreted in terms of differences in organics adsorbed upon the metal surface from one electrolyte to the next. Significance of adsorbed organics upon corrosion rate of steel in sea water is discussed.
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Date Issued: 1979
PURL: http://purl.flvc.org/fcla/dt/13957
Subject Headings: Seawater corrosion
Format: Document (PDF)

Title: Extending use cases and interaction diagrams to develop distributed system architecture requirements.
Creator: Hawkins, John C., Florida Atlantic University, Fernandez, Eduardo B.
Abstract/Description: Current object-oriented development methodologies do not introduce distributed system architectural aspects early enough in the system development cycle. A development partitioning scheme that includes the system level, in addition to the problem and application levels, will encourage analysis that includes elicitation of non-functional system requirements. These requirements include response time with respect to system communication load, fault tolerance, safety, security, and real-time...
Show moreCurrent object-oriented development methodologies do not introduce distributed system architectural aspects early enough in the system development cycle. A development partitioning scheme that includes the system level, in addition to the problem and application levels, will encourage analysis that includes elicitation of non-functional system requirements. These requirements include response time with respect to system communication load, fault tolerance, safety, security, and real-time deadlines, among others. They can be documented with an extended form of Jacobson's use cases. Where use cases describe how a system will work from a user's point of view, extended use cases add the capability to describe how well it should work. System level analysis information can be graphically depicted on extended forms of Unified Modeling Language (UML) interaction diagrams and on multilevel architecture diagrams.
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Date Issued: 1997
PURL: http://purl.flvc.org/fcla/dt/15406
Subject Headings: Object-oriented methods (Computer science), UML (Computer science), Electronic data processing--Distributed processing
Format: Document (PDF)

Title: Facial Expression Computer Interaction System for Children with Asperger's Syndrome.
Creator: Amador, Francisco Javier, Huang, Shihong, Florida Atlantic University
Abstract/Description: People with Autism Spectrum Disorders, particularly Asperger's Syndrome, have a set of symptoms, such as difficulty processing emotive facial expressions and making less eye contact, that affect the individual's social interactions. The prototype developed is geared to help children with Asperger's Syndrome recognize facial expressions, improve eye contact, and to reinforce connections between facial and verbal components of expressions. This application utilizes a computer generated human...
Show morePeople with Autism Spectrum Disorders, particularly Asperger's Syndrome, have a set of symptoms, such as difficulty processing emotive facial expressions and making less eye contact, that affect the individual's social interactions. The prototype developed is geared to help children with Asperger's Syndrome recognize facial expressions, improve eye contact, and to reinforce connections between facial and verbal components of expressions. This application utilizes a computer generated human head, an avatar, to interact with the children while displaying various emotions and using games to increase the children's eye contact. The unique properties of the avatar utilized allow for a comprehensive coverage of the children's attention spectrum to maximize their learning potential. Knowing that about 17% of Autism Spectrum Disorders belong to the Asperger's Syndrome subclass, the positive impact of this application on their life would be of great importance for their families and the community.
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Date Issued: 2010
PURL: http://purl.flvc.org/fau/fd/FA00012503
Subject Headings: Autism spectrum disorders--Treatment--Technological innovations, Optical pattern recognition, Interpersonal communication in children, Emotions in children, Exceptional children--Psychology, Social skills in children
Format: Document (PDF)

Title: A FATIGUE STUDY OF HY-80 STEEL IN SEA WATER.
Creator: ADAMSON, JOHNNY DALE., Florida Atlantic University, Hartt, William H.
Abstract/Description: Fatigue tests were performed at low stresss intensity ranges upon precracxed HY-80 steel specimens in air and sea water, at stress ratios of 0.1 and 0.8 with and without cathodic protection. Crack growth. was found to be higher at R = 0.8 than R = 0.1. Also, the relative positioning of fatigue crack growth rate data for freely corroding and cathodically protected specimens reversed order cs R changed from 0.1 to 0.8. Threshold stress intensity ranges were found to be higher in sea water than...
Show moreFatigue tests were performed at low stresss intensity ranges upon precracxed HY-80 steel specimens in air and sea water, at stress ratios of 0.1 and 0.8 with and without cathodic protection. Crack growth. was found to be higher at R = 0.8 than R = 0.1. Also, the relative positioning of fatigue crack growth rate data for freely corroding and cathodically protected specimens reversed order cs R changed from 0.1 to 0.8. Threshold stress intensity ranges were found to be higher in sea water than in air. A comparison of the deltaKth for HY-80 was made with. that of other steels.
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Date Issued: 1979
PURL: http://purl.flvc.org/fcla/dt/13976
Subject Headings: Steel--Fatigue
Format: Document (PDF)

Title: Experimental analysis of the AUV acoustic signature.
Creator: Frandsen, Susan Eileen., Florida Atlantic University, Cuschieri, Joseph M.
Abstract/Description: This thesis presents an experimental analysis of the acoustic signature of an Ocean Explorer class AUV. The experimental analysis consists of three parts. The first part reports the measurements performed in an open water environment at NSWC in Lake Pend Oreille, Idaho. The second part reports on measurements performed at the FAU test tank on a mock model of the AUV and the third part reports the measurements also in the FAU test tank of the AUV under typical operating conditions. The model...
Show moreThis thesis presents an experimental analysis of the acoustic signature of an Ocean Explorer class AUV. The experimental analysis consists of three parts. The first part reports the measurements performed in an open water environment at NSWC in Lake Pend Oreille, Idaho. The second part reports on measurements performed at the FAU test tank on a mock model of the AUV and the third part reports the measurements also in the FAU test tank of the AUV under typical operating conditions. The model measurement results were also used to verify the prediction capabilities of a numerical FE model of the AUV using the reciprocity method. The measurements in the FAU tank considered different operating conditions and different mounting of the podule inside the AUV. The podule contains the main mechanical components of the AUV, which are the propulsion motor and the control surface motors. Also considered in these measurements is the influence of the propeller and the influence of covering the aft section of the AUV with a compliant layer. The results of this analysis show that the type of mounting of the podule is not very significant and that significant energy is transferred through the water trapped in between the podule and the hull. Furthermore, the propeller has a significant influence on the acoustic signature since it generates distinct tones. These tones were also observed in the results of the open water measurements.
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Date Issued: 2001
PURL: http://purl.flvc.org/fcla/dt/12768
Subject Headings: Underwater acoustics, Oceanographic submersibles
Format: Document (PDF)

Title: Experimental study of the wake-modes for propulsion of two-dimensional heaving airfoils.
Creator: Buzard, Alan Joe., Florida Atlantic University, von Ellenrieder, Karl
Abstract/Description: Particle image velocimetry and flow visualization are used to characterize the wake of a heaving airfoil in a set of two experiments. In the first experiment a tandem airfoil configuration is used, with a stationary airfoil downstream of a heaving airfoil (modified Schmidt wave-propeller). Several vortex structures are identified for a forced Strouhal number (St)---based on airfoil chord-length, forcing frequency, and free-steam velocity---for 0.1
Show moreParticle image velocimetry and flow visualization are used to characterize the wake of a heaving airfoil in a set of two experiments. In the first experiment a tandem airfoil configuration is used, with a stationary airfoil downstream of a heaving airfoil (modified Schmidt wave-propeller). Several vortex structures are identified for a forced Strouhal number (St)---based on airfoil chord-length, forcing frequency, and free-steam velocity---for 0.1 < St < 0.7. An asymmetric average velocity profile is measured in the upper St range. In the second experiment, the wake behind a single heaving airfoil is further inspected, with the purpose of highlighting the asymmetric wake, for 0.1 < St < 1.0. A maximum wake excursion of 18 degrees is measured at St = 0.6, and a minimum excursion of 5.7 degrees occurs at St = 0.9. Using averaged velocity profiles, a virtual origin of the wake excursion is also calculated.
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Date Issued: 2005
PURL: http://purl.flvc.org/fcla/dt/13216
Subject Headings: Particle accelerators--Research, Aerofoils, Aerodynamics, Wakes (Aerodynamics), Flow visualization
Format: Document (PDF)

Title: FRACTURE MECHANICS OF FIBER REINFORCED CONCRETE AND THE DURABILITY OF FIBER REINFORCED AND AIR-ENTRAINED CONCRETE EXPOSED TO FREEZE-THAW CYCLES (FATIGUE).
Creator: JEANFREAU, JAMES JOSEPH, JR., Florida Atlantic University, Arockiasamy, Madasamy
Abstract/Description: This thesis presents the experimental and analytical investigation of fiber (steel and Kevlar) reinforced concrete (FRC) to determine its fracture mechanic properties especially the J-integral. The freeze-thaw durability of fiber reinforced and air-entrained concrete is also investigated. The fiber reinforced concretes were found to have a much greater flexural strength and toughness compared to plain concrete. The compressive strength was found to decrease with the addition of fibers and air...
Show moreThis thesis presents the experimental and analytical investigation of fiber (steel and Kevlar) reinforced concrete (FRC) to determine its fracture mechanic properties especially the J-integral. The freeze-thaw durability of fiber reinforced and air-entrained concrete is also investigated. The fiber reinforced concretes were found to have a much greater flexural strength and toughness compared to plain concrete. The compressive strength was found to decrease with the addition of fibers and air-entrainment. In all cases the addition of 1.0% or more fibers prevented catastrophic failures. The mixing and setting of FRC requires a rigorous procedure which must be followed to achieve a homogeneous matrix.
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Date Issued: 1986
PURL: http://purl.flvc.org/fcla/dt/14334
Subject Headings: Reinforced concrete, Fiber, Fracture mechanics
Format: Document (PDF)

Title: Handwritten digit recognition using neural network integrated chips.
Creator: Bidari, Ravindra Chandrashekar., Florida Atlantic University, Shankar, Ravi
Abstract/Description: Development of a handwritten digit recognition system for real time applications is a feasible goal today due to the many advances pertinent to VLSI. In this research we address the issue of mapping our neural net classification algorithm to Intel's commercially available general purpose Neural Network Chip, 80170NX (ETANN). Most of the proposed techniques used for character recognition have been validated by our research group using various software and hardware simulation methods. The...
Show moreDevelopment of a handwritten digit recognition system for real time applications is a feasible goal today due to the many advances pertinent to VLSI. In this research we address the issue of mapping our neural net classification algorithm to Intel's commercially available general purpose Neural Network Chip, 80170NX (ETANN). Most of the proposed techniques used for character recognition have been validated by our research group using various software and hardware simulation methods. The objective of this thesis was to develop a practical hardware system to perform the final step of classification of handwritten digits in an Optical Character Recognition (OCR) system. Such a hardware implementation would increase the classification speed and also would permit testing in a real life application environment. An efficient mapping scheme was evolved to map the modules of a limited interconnect classification algorithm, CLUMP, to a minimum number of ETANN chips. The hardware modules to interface the ETANN chips to MC68000 education board have been developed and tested. The proposed system is estimated to process the features input in 336 $\mu$s, for our specific implementation, with 12 clock phases and 3 ETANN chips.
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Date Issued: 1992
PURL: http://purl.flvc.org/fcla/dt/14838
Subject Headings: Optical character recognition devices--Computer simulation, Pattern recognition systems--Computer simulation
Format: Document (PDF)

Title: Hierarchical design, simulation and synthesis of a RISC processor using computer-aided design tools.
Creator: Freytag, Glenn A., Florida Atlantic University, Marcovitz, Alan B.
Abstract/Description: The techniques employed in integrated circuit (IC) design have advanced significantly in the past decade. Design automation tools now offer hardware description languages (HDLs) for modeling and testing new designs. Some tools can even synthesize an IC from a model written in an HDL. Such design tools promise to facilitate greatly the development of new IC designs. They also make it possible for engineering students to learn advanced techniques of IC design and computer architecture in a...
Show moreThe techniques employed in integrated circuit (IC) design have advanced significantly in the past decade. Design automation tools now offer hardware description languages (HDLs) for modeling and testing new designs. Some tools can even synthesize an IC from a model written in an HDL. Such design tools promise to facilitate greatly the development of new IC designs. They also make it possible for engineering students to learn advanced techniques of IC design and computer architecture in a classroom setting. Two examples of such state-of-the-art design tools are Design Framework and Epoch. In this work, we present a hierarchical design for a reduced-instruction-set computer (RISC) processor, which we implemented using Design Framework and Epoch. The processor is based on the DLX architecture proposed by Hennessy and Patterson. We implemented our design according to a top-down methodology, which worked very well in these design tools.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/15220
Subject Headings: RISC microprocessors, Computer architecture, Computer-aided design
Format: Document (PDF)

Title: HIGH EFFICIENCY POWER AMPLIFIER DESIGN.
Creator: JONES, LEE JAMES., Florida Atlantic University, Graham, Peter
Abstract/Description: Classes of operation of solid state power amplifiers are surveyed with an emphasis on high efficiency radio frequency applications. Classes A through H and S are covered, with the first three classes combined in a unified analysis. Time domain analyses of the switched-mode classes, D through S, include the effects of stray reactances, switch transition times, and load variations. For class E, a point of optimum operation is derived, and component values are determined assuming optimum...
Show moreClasses of operation of solid state power amplifiers are surveyed with an emphasis on high efficiency radio frequency applications. Classes A through H and S are covered, with the first three classes combined in a unified analysis. Time domain analyses of the switched-mode classes, D through S, include the effects of stray reactances, switch transition times, and load variations. For class E, a point of optimum operation is derived, and component values are determined assuming optimum operation. The multi-resonator and transmission line forms of class F are analyzed. In the last section, audio amplifier and modulator applications of classes G, H, and S are discussed. The characteristics of all the classes of power amplifiers discussed are summarized in a table at the end of the paper.
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Date Issued: 1985
PURL: http://purl.flvc.org/fcla/dt/14276
Subject Headings: Power amplifiers
Format: Document (PDF)

Title: High-Speed High-Frequency Acoustic Communications in Ports and Shallow Water.
Creator: Blue, Patrick Michael, Beaujean, Pierre-Philippe, Florida Atlantic University
Abstract/Description: A detailed study of a novel method for high-speed acoustic communications in ports and shallow water is presented. A series of field experiments, coupled with simulated results using an acoustic channel model have been conducted to outline the optimal modulation schemes for use in the highly reverberant and Doppler dominated shallow water acoustic channel. Field experiments were conducted in the vicinity of the SeaTech marina and the Port Everglades turning basin in water depths of 2 to 15...
Show moreA detailed study of a novel method for high-speed acoustic communications in ports and shallow water is presented. A series of field experiments, coupled with simulated results using an acoustic channel model have been conducted to outline the optimal modulation schemes for use in the highly reverberant and Doppler dominated shallow water acoustic channel. Field experiments were conducted in the vicinity of the SeaTech marina and the Port Everglades turning basin in water depths of 2 to 15 meters and ranges of between 25 and 75 meters. An automated FAU acoustic modem transmitted BPSK and QPSK modulated messages centered at 300 kHz, with a source level of 173 dB re 1pPa and a symbol bandwidth of 25, 50 or 75 kHz. The coded rate varied from 25000 to 150000 bits per second. These high data rates are made possible using a high resolution Decision Feedback Equalizer with an efficient Doppler compensation process. The results of this study demonstrate the ability of such a system to transmit video images in a shallow water environment.
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Date Issued: 2007
PURL: http://purl.flvc.org/fau/fd/FA00012504
Subject Headings: Underwater acoustics, Deep-sea sounding, Seawater--Acoustic properties
Format: Document (PDF)

Title: Highly scalable multiplier.
Creator: Ajmera, Abhijit M., Florida Atlantic University, Shankar, Ravi
Abstract/Description: High speed low power scalable multiplier is needed in computation intensive DSP applications such as video and image compression algorithms. We used an algorithm that folds the larger bit-width operands so smaller bit-width multipliers can be used. Successive folding on operands can be done until a desired threshold is reached. This method has inherent advantages of reuse of optimized building blocks, dynamic reconfiguration, and low power. We implemented a hardware multiplier based on this...
Show moreHigh speed low power scalable multiplier is needed in computation intensive DSP applications such as video and image compression algorithms. We used an algorithm that folds the larger bit-width operands so smaller bit-width multipliers can be used. Successive folding on operands can be done until a desired threshold is reached. This method has inherent advantages of reuse of optimized building blocks, dynamic reconfiguration, and low power. We implemented a hardware multiplier based on this algorithm using Verilog hardware description language. Our results show that this multiplier exhibited significant power advantage over Array and Wallace Tree multipliers for comparable speeds, but had higher gate counts.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/13080
Subject Headings: Digital multipliers--Design and construction, Multipliers (Mathematical analysis), Verilog (Computer hardware description language)
Format: Document (PDF)

Title: IDC - Interim Data Collector: An expert system based upon a relational database management system.
Creator: Cohn, Steven., Florida Atlantic University, Hoffman, Frederick
Abstract/Description: This thesis examines IDC--the Interim Data Collector, a program developed to store diverse technical data in the domain of avionics. The program generates a dialogue through menus and allows rapid data entry and retrieval based on operator supplied information about the modules. The program is written in CLIPPER (a superset of DBASE III+). I will show that IDC exhibits the characteristics associated with programs known as expert systems. These include data directed search, hierarchical...
Show moreThis thesis examines IDC--the Interim Data Collector, a program developed to store diverse technical data in the domain of avionics. The program generates a dialogue through menus and allows rapid data entry and retrieval based on operator supplied information about the modules. The program is written in CLIPPER (a superset of DBASE III+). I will show that IDC exhibits the characteristics associated with programs known as expert systems. These include data directed search, hierarchical dynamic pruning, an interactive user interface and a blackboard type inference engine. I also discuss the various sources of faults which contribute to reliability problems during program use and examine several techniques to increase the reliability of the expert system.
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Date Issued: 1990
PURL: http://purl.flvc.org/fcla/dt/14615
Subject Headings: Avionics--Computer programs
Format: Document (PDF)

Title: Long-term performance of buried high-density polyethylene plastic piping.
Creator: Gazagnaire, Cyril., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: The primary goal of this study was to evaluate the service life of HDPE (High Density PolyEthylene) pipes. The following experimental tasks were carried out: (i) procurement of materials, and fabrication of test setups; (ii) creep evaluation: the performance of buried pipes (notched/unnotched), subjected to live loading, was studied in soil chambers for three levels of loading (service, 2/3 and 1/3 of service). The long-term behavior was accelerated with super-ambient temperatures; (iii)...
Show moreThe primary goal of this study was to evaluate the service life of HDPE (High Density PolyEthylene) pipes. The following experimental tasks were carried out: (i) procurement of materials, and fabrication of test setups; (ii) creep evaluation: the performance of buried pipes (notched/unnotched), subjected to live loading, was studied in soil chambers for three levels of loading (service, 2/3 and 1/3 of service). The long-term behavior was accelerated with super-ambient temperatures; (iii) field monitoring: strains and diametral changes were measured for 10,000 hours. The analytical investigations were as follows: (i) extrapolation of the long-term performance at ambient temperature, based on the Bi-directional and the Arrhenius methods and (ii) 2-D Finite Element Analysis, using the software CANDE. The findings include: (i) the deflection threshold (7.5% vertical change of diameter) as the governing failure condition, (ii) similar life predictions, for Bi-directional and Arrhenius methods, with service lives of about 80 and 30 years at ambient temperature, for unnotched and notched specimens, respectively, subjected to maximum loading, and (iii) a reasonable agreement between analytical and experimental values.
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Date Issued: 2000
PURL: http://purl.flvc.org/fcla/dt/15757
Subject Headings: Pipe, Plastic--Testing, Underground pipelines--Design and construction, Underground plastic pipe
Format: Document (PDF)

Title: Long-term pullout resistance of geogrid reinforcement for retaining walls.
Creator: Gao, Shangsui., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: An experimental and analytical investigation is presented for two types of geogrids: HDPE (High Density Polyethylene) and PET (Polyester). Sand and limerock were used for the backfill material, which meet the FDOT (Florida Department of Transportation) Material Specifications, with simulation of unsaturated and saturated condition. Eight pullout test boxes were designed and constructed, each with a specially designed stainless steel clamp. The measured strain-time relations for unsaturated...
Show moreAn experimental and analytical investigation is presented for two types of geogrids: HDPE (High Density Polyethylene) and PET (Polyester). Sand and limerock were used for the backfill material, which meet the FDOT (Florida Department of Transportation) Material Specifications, with simulation of unsaturated and saturated condition. Eight pullout test boxes were designed and constructed, each with a specially designed stainless steel clamp. The measured strain-time relations for unsaturated and saturated soils for various levels of the pullout force until the peak value (up to 10,000 hours of exposure), and varying distances from the loading end were plotted. The normal and principal stresses in the soil, and the strains along the geogrid were determined from the finite element analysis for the unsaturated soil condition for various pullout force levels. The results were analyzed and a generalized method proposed for practical design using sliding resistance factors.
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Date Issued: 1999
PURL: http://purl.flvc.org/fcla/dt/15689
Subject Headings: Retaining walls, Geogrids, Soil stabilization
Format: Document (PDF)

Title: Missing speech packet reconstruction based on the short-time energy and the zero-crossings.
Creator: Castelluccia, Claude., Florida Atlantic University, Erdol, Nurgun
Abstract/Description: A waveform substitution technique using interpolation based on such slow varying parameters of speech as short-time energy and average zero-crossing rate is developed for a packetized speech communication system. The system uses 64 Kbps conventional PCM for encoding and takes advantage of active talkpurts and silence intervals to increase the utilization efficiency of a digital link. The short-time energy and average zero-crossing rates calculated for the purpose of determining talkpurts are...
Show moreA waveform substitution technique using interpolation based on such slow varying parameters of speech as short-time energy and average zero-crossing rate is developed for a packetized speech communication system. The system uses 64 Kbps conventional PCM for encoding and takes advantage of active talkpurts and silence intervals to increase the utilization efficiency of a digital link. The short-time energy and average zero-crossing rates calculated for the purpose of determining talkpurts are transmitted in a preceeding packet. Hence, when a packet is pronounced "lost", its envelope and frequency characteristics are obtained from the previous packet and used to synthetize a substitution waveform which is free of annoying sounds that are due to abrupt changes in amplitude. Informal listening tests show that tolerable packet loss rate up to 40% are achievable with these procedures.
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Date Issued: 1991
PURL: http://purl.flvc.org/fcla/dt/14704
Subject Headings: Packet switching (Data transmission), Speech processing systems
Format: Document (PDF)

Title: Mobility power flow analysis of connected thick plates with a step discontinuity.
Creator: Faivre d'Arcier, Eric., Florida Atlantic University, Cuschieri, Joseph M.
Abstract/Description: In this thesis the flow of vibration power between two coupled, finite plates of arbitrary thicknesses is considered using a Mobility Power Flow (MPF) approach. The plate structure is divided into substructures and mobility functions are determined for the independent substructures. Power flow expressions are derived based on continuity of forces and displacements. The solution presented here considers the effects of both in-plane waves and out-of-plane waves. The solution is applicable to...
Show moreIn this thesis the flow of vibration power between two coupled, finite plates of arbitrary thicknesses is considered using a Mobility Power Flow (MPF) approach. The plate structure is divided into substructures and mobility functions are determined for the independent substructures. Power flow expressions are derived based on continuity of forces and displacements. The solution presented here considers the effects of both in-plane waves and out-of-plane waves. The solution is applicable to frequencies below the first mode of thickness-shear vibration. The results obtained show that at low frequencies, the out-of-plane waves dominate in the transmission of vibrational power. However, at high frequencies or for thick plates, the in-plane waves play a significant role in the power transmission through the plate.
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Date Issued: 1991
PURL: http://purl.flvc.org/fcla/dt/14705
Subject Headings: Vibration--Measurement
Format: Document (PDF)

Title: Mobility power flow analysis of an infinite cylindrical shell with an enclosed plate discontinuity.
Creator: Buchmann, Patrick Pierre., Florida Atlantic University, Cuschieri, Joseph M.
Abstract/Description: A mobility power flow approach is used to study the response of an infinitely-long cylindrical shell with an internal plate discontinuity. The shell is excited by either a ring radial force or by a plane acoustic wave. The junction between the shell and the internal plate is assumed to be radially pinned such that in-plane waves of the plate can be neglected. The junction forces are expressed in terms of the mobility functions of the plate and the shell. From knowledge of the junction forces...
Show moreA mobility power flow approach is used to study the response of an infinitely-long cylindrical shell with an internal plate discontinuity. The shell is excited by either a ring radial force or by a plane acoustic wave. The junction between the shell and the internal plate is assumed to be radially pinned such that in-plane waves of the plate can be neglected. The junction forces are expressed in terms of the mobility functions of the plate and the shell. From knowledge of the junction forces and velocities, the power input, the power flow from the shell to the plate, the shell response and the radiated far-field scattered pressure are determined for the circumferential mode n = 0. The results show how the energy propagates from one structure to the other, and present a very clear picture of the characteristics of the scattering pattern from the junction forces.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/15113
Subject Headings: Shells (Engineering)--Vibration, Plates (Engineering)--Vibration, Structural dynamics, Vibration
Format: Document (PDF)

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