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Articles 2821 - 2850 of 2903

Full-Text Articles in Engineering

Evaluation Of Texas Cone Penetrometer Test To Predict Undrained Shear Strength Of Clays, Hariharan Vasudevan Aug 2005

Evaluation Of Texas Cone Penetrometer Test To Predict Undrained Shear Strength Of Clays, Hariharan Vasudevan

Civil Engineering Theses - Archive

The cone penetration test used in Texas is termed as Texas cone penetrometer (TCP), which works on dynamic principles similar to those of SPT, i.e. a hammer is used to drive the cone device for a preset depth of penetration of 12 inches. Results are typically reported in the form of N12 values. Correlations between N12 and soil strength properties are currently used by the TxDOT to determine in situ strength properties of soils prior to any infrastructure design. A research study was initiated to evaluate the existing shear strength predicting correlations used by TxDOT and its applicability for soils …

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Water Damage Evaluation Of Concrete Infrastructure, Roshan Shakya Aug 2005

Water Damage Evaluation Of Concrete Infrastructure, Roshan Shakya

Civil Engineering Theses - Archive

This study presents an experimental program to evaluate the effect of a special waterproofing material, International Chem-Crete Pavix (CCP), on the durability of concrete. The experimental program identified the concrete mix design commonly used for pavement and other infrastructure as set by Texas Department of Transportation (TXDOT). The tests conducted include the water absorption and air void (ASTM C 642), freeze-thaw (ASTM C 666), chloride penetration (ASTM C 1202), and petrographic (ASTM C 457) test. The tests were performed on both cored and laboratory treated and untreated specimens. The absorption test was performed on the concrete specimens with water cement …

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Impacts Of Signal Synchronization On Vehicular Emissions - An On-Board Measurement Case Study, Rupangi Munshi Aug 2005

Impacts Of Signal Synchronization On Vehicular Emissions - An On-Board Measurement Case Study, Rupangi Munshi

Civil Engineering Theses - Archive

Nearly 56% of total nitrogen oxide (NOx) emissions are produced by mobile sources. Transportation and air quality managers at the state and regional level have the responsibility of developing and evaluating Transportation Control Measures (TCMs) and Transportation Improvement Plans (TIPs) to improve air quality of the region. Signal synchronization is considered to be an effective TCM to reduce corridor congestion and maintain air quality in the region. This research was carried to determine the impacts of signal synchronization on real-world, on-road emissions. A portable instrument, OBS-1300 manufactured by Horiba Instruments Inc., was used to measure on-road tailpipe emissions of NOx …

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Development Of Finite Element Method-Based Model Equations For Hollow Tapered Poles, Jiwon Jung Aug 2005

Development Of Finite Element Method-Based Model Equations For Hollow Tapered Poles, Jiwon Jung

Civil Engineering Dissertations - Archive

This study presents the development of three-parameter load-deflection models for steel and FRP poles commonly used to support closed circuit television cameras. An experimental investigation is carried out to obtain static load-deflection characteristics of tapered octagonal steel cross section and circular FRP cross section poles. Numerical results generated from three-dimensional isoparametric finite element model (FEM) considering coupled nonlinear algorithms for material, geometric, contact, and pre-tensioning effects are compared with those obtained experimentally. Eight-node elsto-plastic solid element is employed to model the pole, end-plate, bolts, concrete base, and laboratory reaction floor. The laboratory reaction floor is modeled with a thick plate …

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Analysis Of The Dynamics Of Vasomotion Using Laser Doppler Flow, Shruthi Raj Aug 2005

Analysis Of The Dynamics Of Vasomotion Using Laser Doppler Flow, Shruthi Raj

Bioengineering Theses - Archive

Vasomotion is a phenomenon caused by changes in the diameters of blood vessels. It is due to the contractile activity of small arteries and arterioles resulting in periodic changes of blood flow in the skin. These flow variations in the arteries are reflected by the Laser Doppler Flowmeter. The goal of the skin blood flow (blood perfusion) study is to establish a method to analyze and quantify the pattern of vasomotion as detected using Laser Doppler Flow (LDF). Spectral analysis of the LDF signal reveals the presence of periodic components in the vascular system. The study involves twelve subjects of …

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Performance Evaluation Of Bamboo Reinforced Concrete Beams, Leena Khare Aug 2005

Performance Evaluation Of Bamboo Reinforced Concrete Beams, Leena Khare

Civil Engineering Theses - Archive

This study presents the evaluation of the feasibility of the use of bamboo as a potential reinforcement in concrete structural members. To achieve this objective a series of tensile tests on three types of bamboo Solid; Moso; and Tonkin; were conducted to obtain their constitutive relation. Also, four-point bending tests on concrete beams reinforced with bamboo were performed to identify their behavior compared to steel reinforced concrete members. Tensile tests specimens were prepared by cutting the bamboo typically in 1/2 in (13 mm) wide strips of 9 to 12 in (228 mm to 305 mm) in length. In order to …

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Performance And Check-Out Verification Testing Of A New True Triaxial Apparatus Using Partially Saturated Silty Sand, Jae Hyun Park Aug 2005

Performance And Check-Out Verification Testing Of A New True Triaxial Apparatus Using Partially Saturated Silty Sand, Jae Hyun Park

Civil Engineering Theses - Archive

A stress-controlled, flexible boundary, true triaxial (cubical) testing apparatus has been developed to test 3-inch cubical specimen of partially saturated soil under different moisture contents and for a wide range of multiaxial stress paths. A series of HC, CTC, TC, TE, and SS tests were conducted in order to perform a thorough performance and check-out verification testing of the newly developed device by investigating the multiaxial stress-strain response of partially saturated silty sand specimens artificially prepared in the laboratory. The development of the apparatus, specimen preparation process, test procedure, and the corresponding validation of its suitability for testing partially saturated …

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Modeling And Characterization Of A Fabry Perot Pressure Sensor, Shruthika Prasanna Aug 2005

Modeling And Characterization Of A Fabry Perot Pressure Sensor, Shruthika Prasanna

Electrical Engineering Theses - Archive

Fabry-Perot interferometers (FPIs) have been used as sensing elements for pressure transducers in many applications. Most of the current FPI pressure sensors measure amplitude changes of the reflected signals from a deformable diaphragm. A new technique to design an FPI pressure sensor has been proposed in this thesis. The proposed methodology aims to maximize the sensitivity by measuring frequency shifts and optimize the dimensions of the sensors for various materials and applications. The sensor diaphragm is built directly on the end surface of an optical fiber with a sacrificial layer introducing the required FPI cavity height. The resulting sensor detects …

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Physics Based Time-Frequency Analysis To Reduce Multi-Bounce And Clutter In Radar Imaging, Anilkumar Kollipara Aug 2005

Physics Based Time-Frequency Analysis To Reduce Multi-Bounce And Clutter In Radar Imaging, Anilkumar Kollipara

Electrical Engineering Theses - Archive

The concept of time-frequency analysis of the scattered far field data from multiple targets is presented. The scattered data from the target is collected using a mono-static antenna configuration. The hardware system and the data acquisition system used in the process are discussed in detail. The results obtained using the ISAR imaging algorithm are presented and the effect of different non-point and dispersive scattering phenomena on these images are discussed. A physics based time-frequency analysis using wavelets is done on this scattered data to reduce the inter-target interactions and thereby produce cleaner images of the target under consideration. The results …

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Optical Amplifiers For 10 Gb/S Wdm Recirculating Loop Testbed, Sravanthi Thotakura Aug 2005

Optical Amplifiers For 10 Gb/S Wdm Recirculating Loop Testbed, Sravanthi Thotakura

Electrical Engineering Theses - Archive

This Master's thesis deals with building experimental setup for characterization of novel nonlinear optical devices for fiber communication. The first part of the thesis deals with the description of the theoretical basis for operation of a particular type of such nonlinear optical devices, namely a parametric amplifier. Document includes deriving and solving the equations for parametric amplification in optical fiber when signal, idler and pump beams are linearly co-polarized. We consider both non-degenerate and degenerate pump cases for arbitrary phase mismatch. In the second part of the thesis we present the design and experimental implementation of electrical interface between commercial …

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Time Synchronization In Network-Centric Sensor Networks, Sejal D. Raje Aug 2005

Time Synchronization In Network-Centric Sensor Networks, Sejal D. Raje

Electrical Engineering Theses - Archive

Time synchronization is a crucial component of infrastructure for wireless sensor networks (WSN). Most applications of WSNs make extensive use of time synchronization, for accurate timestamping of events, coordinate activities of the network, data fusion, object tracking or TDMA scheduling. The unique requirements of sensor networks in terms of precision, lifetime, energy and scope of the synchronization achieved, calls for design of new synchronization methods for WSNs. In this thesis, we describe the design of three novel techniques for achieving synchronization in network centric scenario of sensor networks: sequential least squares, Kalman filter and fuzzy logic systems. The strength of …

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Collision Response For Virtual Laparoscopic Surgery, Jitesh Devidas Butala Aug 2005

Collision Response For Virtual Laparoscopic Surgery, Jitesh Devidas Butala

Electrical Engineering Theses - Archive

During laparoscopic surgery the surgeon operates inside the abdomen guided by the 2D imagery of the operating area. This image is obtained via a camera inserted through a small incision. Laparoscopic surgery, in contrast to open surgery, results in low pain and recovery time for the patient. However, the surgeons have some difficulty, as the training required for this type of surgery is more intense and rigorous than that for conventional open surgery. Hence, surgical trainers for laparoscopic surgery are important. The main difference in the different types of surgical trainers is the degree to which the actual environment of …

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Structure & Decision In Mobile Wireless Sensor Networks, Prasanna Mohan Ballal Aug 2005

Structure & Decision In Mobile Wireless Sensor Networks, Prasanna Mohan Ballal

Electrical Engineering Theses - Archive

This work concerns the development of a novel structure of Discrete Event Controller (DEC) for mobile wireless sensor networks consisting of mobile robots and stationary wireless sensing nodes known as Unattended Ground Sensors (UGS). These are the three contributions: 1. Decision-making systems such as Fuzzy Logic and Dempster Shafer Theory for sensor fusion are implemented. 2. Decision-making is used for a special case of routing of resources for multiple tasks performed by different resources. 3. The DEC was actually implemented in the Mobile Wireless Sensor Networks lab at Automation & Robotics Research Institute. This work was supported by ARO grant …

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Vascular Stent Analysis, Tre Raymond Welch Aug 2005

Vascular Stent Analysis, Tre Raymond Welch

Bioengineering Theses - Archive

It is important for cardiologist to understand the stresses and strains the stent experiences during deployment. We created a 3-D model of the coiled stent which is exported into ANSYS creating the finite element model. The stent material is Poly-L-Lactic Acid (PLLA) fiber with a Young's modulus of 7043(MPa) and a Poisson's ratio of 0.35. A nonlinear material analysis simulates the material behavior through plastic deformation during expansion from 1(atm) to 14(atm). The von Mises stresses, principal stresses, and principal strains are analyzed to determine the yielding of the PLLA fiber. Also, the effect of different material properties including Young's …

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Near Infrared Spectroscopy: A Study Of Cerebral Hemodynamics During Breathholding And Development Of A System For Hot Flash Measurement, Vikrant Sharma Aug 2005

Near Infrared Spectroscopy: A Study Of Cerebral Hemodynamics During Breathholding And Development Of A System For Hot Flash Measurement, Vikrant Sharma

Bioengineering Theses - Archive

Near Infrared (NIR) spectroscopy and imaging has become popular in research fields for the past 2-3 decades. My research focuses on the continuous wave near infrared imaging technique. The work consists of two main parts. In the first part, an existing commercial system, an LEDI (Light Emitting Diode Imager), is used to study the cerebral hemodynamics during breath holding. The aim was to evaluate the ability of an LED-based continuous wave imager to capture changes in hemodynamics occurring inside the skull induced by breath holding. The study involved 15 human subjects. It was found that the total hemoglobin concentration (in …

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Dynamic Modeling Of Cerebral Blood Flow Autoregulation Using Arx And Windkessel Models, Piyush Gehalot Aug 2005

Dynamic Modeling Of Cerebral Blood Flow Autoregulation Using Arx And Windkessel Models, Piyush Gehalot

Bioengineering Theses - Archive

Linear lumped parameter models like ARX and Windkessel models are simple, easy to solve, and find their application in real time modeling. The present study is focused on employing single input single output ARX and Windkessel models to beat-to-beat mean arterial blood pressure (MABP, mmHg) considered as input to the model, and cerebral blood flow velocity (CBFV, cm/sec) considered as output of the model. For some models and modeling methodologies, the data consisted of cerebral perfusion pressure (CPP, mmHg, estimated from MABP) and CBFV. The data was measured from 10 healthy normal subjects while the subjects performed Valsalva maneuver with …

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Piezoelectric Analysis For Hetrogeneous Medium, Solmaz Torabi Aug 2005

Piezoelectric Analysis For Hetrogeneous Medium, Solmaz Torabi

Material Science and Engineering Theses - Archive

In the recent years, several types of piezocomposites have been fabricated since they have provided material properties superior to conventional piezoelectric materials. In order to design these composites, it is essential to find the elastic and electric fields for their different parts, as well as the effective properties of the composite. In the present study, the analytical approach based on the extension of Eshelby's theory in piezoelectricity and the numerical approach based on FEM modeling and ANSYS software have been used to find these elastic and electric fields inside the piezoceramic inhomogeneity for two different piezocomposite according to their connectivity, …

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Nonlinear H2/H∞ Constrained Feedback Control: A Practical Design Approach Using Neural Networks, Murad Abu-Khalaf Aug 2005

Nonlinear H2/H∞ Constrained Feedback Control: A Practical Design Approach Using Neural Networks, Murad Abu-Khalaf

Electrical Engineering Dissertations - Archive

In this research, practical methods for the design of H2 and H8 optimal state feedback controllers for constrained input systems are proposed. The dynamic programming principle is used along with special quasi-norms to derive the structure of both the saturated H2 and H8 optimal controllers in feedback strategy form. The resulting Hamilton-Jacobi-Bellman (HJB) and Hamilton-Jacobi-Isaacs (HJI) equations are derived respectively. It is shown that introducing quasi-norms on the constrained input in the performance functional allows unconstrained minimization of the Hamiltonian of the corresponding optimal control problem. Moreover, it is shown how to obtain nearly optimal minimum-time and constrained state controllers …

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Low Phase Noise Voltage-Controlled Oscillator Design, Zhipeng Zhu Aug 2005

Low Phase Noise Voltage-Controlled Oscillator Design, Zhipeng Zhu

Electrical Engineering Dissertations - Archive

Two kinds of voltage-controlled oscillators (VCO) - active inductor based VCO and LC cross-coupled VCO - are studied in this work. Although the phase noise performance is not competitive, the proposed active inductor based VCO provide an alternative method to VCO design with very small chip area and large tuning range. The measurement shows a test oscillator based on active inductor topology successfully oscillates near 530MHz band. The phase noise of the widely used LC cross-coupled VCO is extensively investigated in this work. Under the widely used power dissipation and chip area constraints, a novel optimization procedure in LC oscillator …

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Power Management Integrated Circuits Design, Functionality Analysis And Applications, Zheng Li Aug 2005

Power Management Integrated Circuits Design, Functionality Analysis And Applications, Zheng Li

Electrical Engineering Dissertations - Archive

Power management is playing a significant role in modern electronics. Good power management is especially important for portable devices that rely on batteries. By smartly managing how the power is directed to different components of a system, e.g., reducing power to components that are not being used, the efficiency as well as the battery lifetime can be doubled or tripled. There exists a large family of integrated circuits (IC) that are used for power management, e.g., linear regulators, switching regulators, power controllers, hot swap controllers, etc. The voltage reference is one of the key components in this family. For high …

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The Operation Platform Recommendation For The Deregulated Utility Industry In Thailand, Chai Chompoo-Inwai Aug 2005

The Operation Platform Recommendation For The Deregulated Utility Industry In Thailand, Chai Chompoo-Inwai

Electrical Engineering Dissertations - Archive

Transmission Congestion Management (TCM) plays a significant role in power system operation under today deregulated environment. It has two major functions of an apparatus to keep power system running within acceptable security limits, and of a tool allocating financial obligation to market participants then paying back to transmission grid investors. TCM issue has been widely debating during a past decade, until now, it is still an opened issue extensively discussed in the current structure of competitive environment. In the United State, there are existing two successful stories of TCM under different operation schemes, the former is PJM with Nodal Congestion …

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Shared Data Acquisition System For Real-Time Power Systems Applications, Yi-Fang Hsu Aug 2005

Shared Data Acquisition System For Real-Time Power Systems Applications, Yi-Fang Hsu

Electrical Engineering Theses - Archive

Digital signal processing chip (DSP's) can be used to perform data analysis computation and have very good performance in real-time system. Digital filters can be designed with consideration of both magnitude and phase responses for digital re-sampling in power system applications. The design consists of two parts: magnitude approximation and group delay compensation. It compromises between the amount of calculation needed to implement the filters and the performance of the filters, which makes the filters good candidates for both real-time and offline applications.

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Biomechanical Properties Of Anterior Vaginal Wall Tissue In Post-Menopausal Women, Aradhana Bhatt Aug 2005

Biomechanical Properties Of Anterior Vaginal Wall Tissue In Post-Menopausal Women, Aradhana Bhatt

Bioengineering Theses - Archive

Cystocele repair in post-menopausal women suffering from urinary incontinence and associated vaginal prolapse is a common method of palliation. In this method, there is surgical reduction of vaginal tissue and the weak cross-sections are often supported with a synthetic sling fashioned from polymer mesh material. Some sling-supported and unsupported repairs fail over the years. The reasons for these failures are unclear, due in part to a lack of fundamental knowledge of the mechanisms associated with cystocele and vaginal prolapse. The aim of this study was to understand the mechanisms of tissue failure by biomechanical and ultrastructural studies. We take advantage …

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Polymer Tube Embedded In-Plane Micropump: Design, Analysis And Fabrication, Ashutosh Kole Aug 2005

Polymer Tube Embedded In-Plane Micropump: Design, Analysis And Fabrication, Ashutosh Kole

Mechanical and Aerospace Engineering Theses - Archive

This thesis presents the design, analysis, and fabrication of a novel polymer tube embedded in-plane micropump. The key component of the proposed micropump is a Parylene polymer tube that is embedded into the trench of a silicon die. Advantages of embedding a Parylene polymer tube are biocompatibility and leakage free environments. The issue of leakage of fluid presented in [1] is eliminated by inserting the polymer tube. The tube itself acts as a diaphragm, which transfers the force and motion of thermal actuators to fluid. The structural analysis and the fabrication of the Parylene tube along with the coupled-field multiphysics …

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Analysis And Modeling Of A Micro Variable Capacitance Electromechanical Energy Converter, Amita Jindal Aug 2005

Analysis And Modeling Of A Micro Variable Capacitance Electromechanical Energy Converter, Amita Jindal

Electrical Engineering Theses - Archive

Research and development in microelectromechanical systems (MEMS) have made remarkable progress since 1988. Micro-machines are an integral part of MEMS. However, these machines are not often discussed in most electric machines, power electronics and drive forums due to the relative newness of these machines. This thesis provides an in-depth analysis of a variable capacitance micro-machine (VCM). It gives an insight into the effects of machine geometry, on capacitance and torque profiles of the machine. Tangential and radial components of the electrostatic forces in the air gap of the machine have been investigated to study the effects of mutual flux. These …

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Nonlinear Finite Element Model Analysis Of Human Accommodation Lens, Tri Le Aug 2005

Nonlinear Finite Element Model Analysis Of Human Accommodation Lens, Tri Le

Civil Engineering Theses - Archive

The crystalline human lens is modeled by using the finite element software, ABAQUS/CAE Version 6.5-1 as an axisymmetric shell to study the optical power and displacement of anterior and posterior poles induced due to zonule traction. Several different element types were tested to obtain the optimum mesh. These elements were three and six-noded triangular hybrid and four-noded quadrilateral hybrid for modeling of the cortex and nucleus. Constant strain triangular and regular quadrilateral elements were examined for modeling the capsule. One dimensional two degree of freedom spring elements were used to model the anterior, posterior, and equatorial zonules. Five different lens …

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Cathodic Electrodeposition Of Cadmium Oxide, Zinc Oxide And Mixed Cadmium Oxide-Zinc Oxide Thin Films, Ashwin Seshadri Aug 2005

Cathodic Electrodeposition Of Cadmium Oxide, Zinc Oxide And Mixed Cadmium Oxide-Zinc Oxide Thin Films, Ashwin Seshadri

Material Science and Engineering Theses - Archive

Cadmium oxide (CdO) and (CdO)x(ZnO)1-x mixed semiconductor films were cathodically electrodeposited for the first time on F-doped SnO2 substrates. The CdO thin films were deposited from an aqueous 0.1 M KCl medium containing dissolved Cd2+ species and O2. The (CdO)x(ZnO)1-x mixed oxide films were deposited from a bath which contained Zn2+ in addition to the CdO bath constituents. Films were potentiostatically deposited at 80 0C followed by a post-deposition thermal anneal at 450 0C. The mechanism of the electrodeposition was explored using cyclic voltammetry. These samples were then analyzed by X-ray diffraction, scanning electron microscopy, and UV-visible reflectance spectrophotometry. The …

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Study Of Blast Wave Impact On Concrete, Ajit Geevarghese John Jul 2005

Study Of Blast Wave Impact On Concrete, Ajit Geevarghese John

Mechanical and Aerospace Engineering Theses - Archive

The past decade has brought an upsurge of terrorist attacks throughout the world. A common form of attack is bombings employed against a civilian structure. These bombs lead to blast waves resulting from high explosive bursts in air, causing severe structural damage to buildings that often collapse before evacuation is possible. These blast waves subject the buildings to repeated dynamic loading in the form of reflecting shock waves which then finally lead to their destruction. Many studies have been carried out to understand the static loading of these structures. The current study is to protect existing buildings from an explosion. …

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Research For Dynamic Seal Friction Modeling In Linear Motion Hydraulic Piston Applications, Brian Edward Suisse Jul 2005

Research For Dynamic Seal Friction Modeling In Linear Motion Hydraulic Piston Applications, Brian Edward Suisse

Mechanical and Aerospace Engineering Theses - Archive

This paper presents a unique physics-based analytic model for dynamic seal friction in hydraulic actuators as a function of cylinder pressure, seal material, piston rod dimensions, piston rod seal gland dimensions, and other influencing factors. Results from a series of friction tests are presented. Finite element analysis of an installed seal is used to predict contact stress between the seal and the gland, providing a normal force against the sealing surface. This information is used to determine coefficients of friction within the test specimen. From the analysis, a pressure-sensitive model is generated. The friction model is overlaid on the test …

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Investigation Of Minimum Response For Damage Assessment, Jeffrey Kirk Jul 2005

Investigation Of Minimum Response For Damage Assessment, Jeffrey Kirk

Mechanical and Aerospace Engineering Theses - Archive

Assessment of structural damage based on changes in vibratory response characteristics has been researched for many years, with much attention directed toward the use of modal parameters. Modal responses contribute to form points of local minima in the frequency response of a system. The frequency and amplitude values corresponding to these points of minimum response can be analytically determined, experimentally measured, and shown to exhibit sensitivity to damage. This work was performed to investigate the possible contribution that explicitly targeted minimum response information could provide in a damage detection process. A simple 6-DOF discrete spring-mass system was used to conduct …

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