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Computer Simulation, Fabrication And Characterization Of Inverse Frustum Nanosphere Metal Arrays For Fiber-Based Plasmonic Sensors, Jiaqi Wu Jan 2012

Computer Simulation, Fabrication And Characterization Of Inverse Frustum Nanosphere Metal Arrays For Fiber-Based Plasmonic Sensors, Jiaqi Wu

Material Science and Engineering Theses - Archive

In recent years, a number of metal nanostructures have attracted huge attention from scientists and researchers for its plasmonic property and surface enhanced Raman scattering effect. They have been utilized to monitor molecule adsorption, antibody-antigen reorganization event, and to enhance scattering for identification of molecules even in very low concentration. They both have also been exploited for real time biosensing.In this thesis, we are investigating a new plasmonic structure, inverse frustum nanosphere gold arrays, and exploring its optical fiber-based sensing application. The nanostructure was fabricated by electro-deposition of gold into pre-assembled templates, which are made of monodispered colloidal polystyrene nanospheres …

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Cuinse2: Electronic Activities Of Grain Boundaries And Solar Cell Fabrication Studies, Mehmet Eray Erkan Jan 2012

Cuinse2: Electronic Activities Of Grain Boundaries And Solar Cell Fabrication Studies, Mehmet Eray Erkan

Material Science and Engineering Dissertations - Archive

This dissertation is composed of three studies related to chalcopyrite solar cells. The first study is on electronic activities of grain boundaries (GBs) in CuInSe2 (CIS). Despite being polycrystalline, chalcopyrite thin film solar cells have reached record power conversion efficiencies. This is against the classical understanding on the effect of GBs in semiconductor materials. Because GBs are expected to be recombination centers and barriers against the carrier flow, reducing the device efficiency. Therefore, a complete understanding on the electronic behavior of chalcopyrite GBs is missing. Moreover, the high efficiency chalcopyrite solar cells are grown with Na impurities which positively …

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Solution To Three Dimensional Incompressible Navier-Stokes Equations Using Finite Element Method, Shrinivas Ganesh Apte Jan 2012

Solution To Three Dimensional Incompressible Navier-Stokes Equations Using Finite Element Method, Shrinivas Ganesh Apte

Mechanical and Aerospace Engineering Theses - Archive

A primitive variable mixed order formulation of finite element method for solving three dimensional incompressible Navier-Stokes equations is presented. The method of weighted residuals is used to obtain the approximate solutions of linear and nonlinear partial differential equations. The physical domain is discretized by using unstructured tetrahedral elements. Unequal order interpolation functions are used for pressure & velocity variables while the temporal discretization is carried out by using an implicit time marching scheme based on finite differencing.One of the major difficulties arising during the finite element solution of the incompressible Navier-Stokes equations is the efficient factorization/preconditioning of the resulting indefinite …

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High Enthalpy Characterization Of The Uta Hypersonic Shock Tunnel, Raheem Temitope Bello Jan 2012

High Enthalpy Characterization Of The Uta Hypersonic Shock Tunnel, Raheem Temitope Bello

Mechanical and Aerospace Engineering Theses - Archive

In hypersonic wind tunnel testing, matching the flow enthalpy conditions for the hypersonic air-breathing corridor is of great importance in order to assure the validity of experimental results. The flow enthalpy of the UTA hypersonic shock tunnel is increased by a shock induced detonation driver. The detonation mixture consist of hydrogen and oxygen in stoichiometric quantities ( 2H2+O2 ? 2H2O). Experimental variations of pressure and the volume of the detonation section were performed to characterize the enthalpy limits, and overall performance of the UTA hypersonic shock tunnel. The UTA HST test section is designed for a nominal Mach number of …

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Wear And Tribofilm Formation With Zinc-Free Antiwear Additives, Pradip Sairam Pichumani Jan 2012

Wear And Tribofilm Formation With Zinc-Free Antiwear Additives, Pradip Sairam Pichumani

Material Science and Engineering Theses - Archive

Engine oil is used in all internal combustion engines to lubricate the moving parts & mitigate the wear due to friction. Along with the mentioned two functions, engine oil also serves to protect the engine from corrosion, clean debris, improves sealing and serves in thermal conductivity. Engine oil is either derived from petroleum derivatives or made synthetically. A number of additives are added to the engine oil (Base oil) to improve its performance and longevity. Antioxidants, pour point depressants, viscosity index improvers, antifoaming agents, corrosion inhibitors, etc are some of the additives that are added to improve the engine oil‘s …

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Experimental And Numerical Investigation Of Mass Transfer In Microreactors, Wei-Tsen Han Jan 2012

Experimental And Numerical Investigation Of Mass Transfer In Microreactors, Wei-Tsen Han

Mechanical and Aerospace Engineering Dissertations - Archive

In this work, two types of microreactors for reactions have been studied, which were involving multiple fluid phases: liquid-liquid (immiscible liquids) phase and gas-liquid phase. Investigation of mass transfer within reacting flows in microreactors has been carried out in these two multiphase systems. For the liquid-liquid phase, a microfluidic system was designed and fabricated to generate a slug flow pattern of immiscible liquids. This system was used to demonstrate the effect of the flow pattern on mass transfer and the effect on chemical reaction rate for a simple acid-base reaction. The reaction progression was tracked by measuring the pH along …

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Hydrological Visualization And Analysis System And Drought Related Feature Selection Based On Sectional Correlation Measurement, Piraporn Jangyodsuk Jan 2012

Hydrological Visualization And Analysis System And Drought Related Feature Selection Based On Sectional Correlation Measurement, Piraporn Jangyodsuk

Computer Science and Engineering Theses - Archive

Because of the larger data storage and the faster computational power, computer can process and store much finer resolution data. Aside from data analysis, data visualization is also an important task to understand the data. In this work, the Hydrological Visualization and Analysis System is developed to help both hydrologists and local people view and examine the high resolution hydrological data. Then, this data is analyzed to determine which variables are related to the change of drought condition in Arlington, Texas. A new correlation measurement method called sectional correlation is proposed and used as an objective function of the drought …

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Dynamic Cache Reconfiguration For Energy Optimization In Chip Multiprocessors, Gaurav Puri Jan 2012

Dynamic Cache Reconfiguration For Energy Optimization In Chip Multiprocessors, Gaurav Puri

Computer Science and Engineering Theses - Archive

Cache reconfiguration for chip multiprocessors (CMP) in order to reduce energy consumption is a challenging research problem. This thesis presents a dynamic scheme for level one cache design where the processing core can dynamically switch to a lower energy configuration. The proposed scheme is based on a heuristic that can either be executed as part of the firmware or implemented in hardware with very low additional overhead. The heuristic functions periodically after a pre-defined fixed interval for each processing core. The heuristic first examines the statistics calculated over the previous intervals and then switches the cache to an improved configuration …

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Automatic Scheduler: A New Approach For Scheduling Rides, Amey Sudhir Bhalerao Jan 2012

Automatic Scheduler: A New Approach For Scheduling Rides, Amey Sudhir Bhalerao

Computer Science and Engineering Theses - Archive

Scheduling plays an important role in a person's life. Even computers use the concept of scheduling when it comes to processing jobs. Scheduling is important in cases normally when there is large data to process and manual scheduling is not an easy option to go for. A new concept of developing a scheduler has been discussed in this thesis. The algorithm was designed keeping in mind the Para Transit agencies that operate on federal funds to provide cheap transport service to the clients. The algorithm presented here is developed with the intention to reduce the delay faced by the client …

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Querying Entity-Relationship Graphs By Example Tuples: Experimental Evaluation And User Study, Mahesh Gupta Jan 2012

Querying Entity-Relationship Graphs By Example Tuples: Experimental Evaluation And User Study, Mahesh Gupta

Computer Science and Engineering Theses - Archive

The World Wide Web today has evolved into a rich repository of entities where many knowledge bases containing entity-related information are directly available. Such knowledge bases are often in the form of entity-relationship graphs. To query entity-relationship graphs, users need to provide input entities, attributes and relationships by complex query graphs. To improve the usability of graph database systems, we study a novel mechanism that queriesentity-relationship graphs by example tuples. It allows users to express a query in the form of one or more tuples consisting of entities. The underlying query system automatically builds aquery graph based on the example …

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Experimental Identification Of Force Coefficients Of Hybrid Air Foil Bearings, Yu Ping Wang Jan 2012

Experimental Identification Of Force Coefficients Of Hybrid Air Foil Bearings, Yu Ping Wang

Mechanical and Aerospace Engineering Theses - Archive

Successful applications for air foil bearings in small to midsize turbo-machinery have been acknowledged. Air foil bearings do not require oil lubricant thus they are capable of operating under much higher temperature than oil-lubricated bearings and they entail less maintenance costs if well-designed. However, when rotor size increases beyond 100 mm in diameter, reliability becomes an issue due to comparable increase in rotor weight with respect to increase in load capacity of the bearing. Furthermore, dry rubbing during starts and stops also causes concerns due to typical slow acceleration and deceleration characteristics of large turbo-machinery. The concept of hybrid air …

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Experimental Feasibility Study Of Radial Injection Cooling Of Three-Pad Radial Air Foil Bearings, Suman K. Shrestha Jan 2012

Experimental Feasibility Study Of Radial Injection Cooling Of Three-Pad Radial Air Foil Bearings, Suman K. Shrestha

Mechanical and Aerospace Engineering Theses - Archive

Air foil bearings use ambient air as a lubricant allowing environment-friendly operation. When they are designed, installed, and operated properly, air foil bearings are very cost effective and reliable solution to oil-free turbomachinery. Because air is used as a lubricant, there are no mechanical contacts between the rotor and bearings and when the rotor is lifted off the bearing, near frictionless quiet operation is possible. However, due to the high speed operation, thermal management is one of the very important design factors to consider. Most widely accepted practice of the cooling method is axial cooling, which uses cooling air passing …

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Thermal Behavior Of Dielectric Materials During Rapid Heating, Daipayan Sarkar Jan 2012

Thermal Behavior Of Dielectric Materials During Rapid Heating, Daipayan Sarkar

Mechanical and Aerospace Engineering Theses - Archive

The objective of this research is to understand the temperature variation in dielectric materials of different geometry. The work is divided into three major segments. The Thermal Wave model has been taken into consideration as the classical Fourier law of heat conduction breaks down when a dielectric material of sub-micron geometry is heated rapidly. The first partof the work discusses primarily about the temperature distribution in a semi-infinite dielectric material, followed by the temperature profile in a finite body (plate) and finally mathematical formulation is presented for a two-layered body. The thermal wave equation is used because in dielectric materials …

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Mitigation Of Hot-Spots In High-End Microprocessors Using Bulk And Thin Film Thermoelectric Coolers, Agat Hirachan Jan 2012

Mitigation Of Hot-Spots In High-End Microprocessors Using Bulk And Thin Film Thermoelectric Coolers, Agat Hirachan

Mechanical and Aerospace Engineering Theses - Archive

Due to localized high heat fluxes, hot-spots are created in silicon chips. Cooling of the hot-spots is one of the major thermal challenges in today's integrated circuit (IC) industry. Many researches have been conducted to find ways to cool hot-spots using different techniques as uniform heating is highly desired. First part of the thesis focuses on cooling of hot-spot using conventional thermoelectric cooler (Melcor_CP1.0-31-05L.1) and a micro heat pipe. A chip package with conventional integrated heat spreader and heat sink was designed. Hot-spot was created at the center of the silicon die with background heat at rest of the area. …

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Dynamic Performance Of Offset-Preloaded Two Pad Foil Bearings, Shrikant Ashok Yadav Jan 2012

Dynamic Performance Of Offset-Preloaded Two Pad Foil Bearings, Shrikant Ashok Yadav

Mechanical and Aerospace Engineering Theses - Archive

Commercial application of the air foil bearing (AFB) in microturbomachinary have been acknowledged. Absence of external pressurizing and lubricating system makes them light and compact. Simple construction, low friction drag and reliability at high speed operations are few more advantages of the AFBs. With all these advantages AFB proves to be the suitable option for oil-free small turbomachinery which includes micro gas turbines with shaft power less than 1000hp. Micro gas turbine generators are typically two shaft configuration with power generation capacity less than 500KW. Although many micro gas turbines with AFBs have been developed, due to the proprietary nature …

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Dynamic Mode Decomposition Of Detonation Waves, Rahul Kumar Jan 2012

Dynamic Mode Decomposition Of Detonation Waves, Rahul Kumar

Mechanical and Aerospace Engineering Theses - Archive

Dynamic mode decomposition is applied to study the self-excited fluctuations supported by transversely unstable detonations. The focus of this study is on the effect of forcing on the limit cycle solutions. Using DMD, only the most coherent modes are analyzed. The most coherent modes in this case are the fundamental and the fourth harmonic. The analysis is based on the coherency of the self-excited detonation modes due to turbulence. Analysis reveals coherency is significantly affected with a turbulent Mach number greater than 0.3 and also the regions downstream of the shock are more affected by turbulence than the region just …

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Trajectory Generation And Constrained Control Of Quadrotors, Carlos Alberto Tule Jan 2012

Trajectory Generation And Constrained Control Of Quadrotors, Carlos Alberto Tule

Mechanical and Aerospace Engineering Theses - Archive

Unmanned Aerial Systems, although still in early development, are expected to grow in both the military and civil sectors. As part of the UAV sector, the quadrotor helicopter platform has been receiving a lot of interest from various academic and research institutions because of their simplistic design and low cost to manufacture, yet remaining a challenging platform to control. Four different controllers were derived for the trajectory generation and constrained control of a quadrotor platform. The rst approach involves the linear version of the Model Predictive Control (MPC) algorithm to solve the state constrained optimization problem. The second approach uses …

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Stress Analysis In Curved Composite Due To Thermal Loading, Jared Cornelius Polk Jan 2012

Stress Analysis In Curved Composite Due To Thermal Loading, Jared Cornelius Polk

Mechanical and Aerospace Engineering Theses - Archive

Many structures in aircraft, cars, trucks, ships, machines, tools, bridges, and buildings, consist of curved sections. These sections vary from straight line segments that have curvature at either one or both ends, segments with compound curvatures, segments with two mutually perpendicular curvatures or Gaussian curvatures, and segments with a simple curvature. With the advancements made in multi-purpose composites over the past 60 years, composites slowly but steadily have been appearing in these various vehicles, compound structures, and buildings. These composite sections provide added benefits over isotropic, polymeric, and ceramic materials by generally having a higher specific strength, higher specific stiffnesses, …

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Using Gpu-Based Computing To Accelerate Finite Element Problems, Jacob Watt Jan 2012

Using Gpu-Based Computing To Accelerate Finite Element Problems, Jacob Watt

Mechanical and Aerospace Engineering Theses - Archive

Historically Graphics Processing Units (GPU) have been used for offloading graphical visualization and made popular in use for video games, but with the development of NVIDIA's CUDA architecture and programing language there has been an increase in the use of GPUs in general purpose (GPGPU) programing. Problems involving large systems of linear equations, such as the Finite Element Analysis (FEA), can benefit greatly from the parallel computing capabilities of GPUs. In my thesis I will solve Poisson's equation and discuss the advantages and disadvantages of the massively parallel environment of GPUs. I will show that on a unstructured grid that …

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Determination Of Factors To Improve Effectiveness Of Triangulation Members For A Formula Sae Race Car Frame, Vikram Nair Jan 2012

Determination Of Factors To Improve Effectiveness Of Triangulation Members For A Formula Sae Race Car Frame, Vikram Nair

Mechanical and Aerospace Engineering Theses - Archive

This thesis suggests which factors have significant effect on the torsional and flexural stiffness of a space frame without contributing excessively to its weight. These factors are used as design variables to display the interaction plots generated by performing a Design of Experiments (DOE) using the Hyperstudy tool in Hyperworks by Altair®. The DOE will also provide a mathematical model which can help predict the responses by varying several factors in the design. The node - element models are created in ANSYS classic and are analyzed for various load cases that are representative of the loads on a formula SAE …

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Characterization Of Uta Hypersonic Shock Tunnel, Derek Glenn Leamon Jan 2012

Characterization Of Uta Hypersonic Shock Tunnel, Derek Glenn Leamon

Mechanical and Aerospace Engineering Theses - Archive

Characterization of a hypersonic shock tunnel was performed under low enthalpy conditions. A rake was designed and fabricated to measure pitot pressure and heat flux at three axial locations in the test section. Pitot pressures at three locations provided an indication of the inviscid core. Thin film RTD sensors with a fast response time were fabricated to measure the heat flux under these low enthalpy conditions. The Cook-Felderman algorithm was used to estimate the heat flux from the temperature history. Results for the first millisecond of test time showed a probe tip surface temperature increase of 15-20 K and a …

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Computational Study Of Heat Transfer Enhancement For A Dimpled Surface In A Channel, Abhijit Paranjape Jan 2012

Computational Study Of Heat Transfer Enhancement For A Dimpled Surface In A Channel, Abhijit Paranjape

Mechanical and Aerospace Engineering Theses - Archive

Heat transfer augmentation techniques have gained great importance in different engineering applications to deal with thermal management issues. In this work, a numerical investigation was carried out to see the effects of spherical dimple arrays on heat transfer characteristics in a channel. These effects were observed for dimples on the bottom wall of the channel for laminar airflows. The effects of a 21×7 staggered array and a 19×4 inline array on the bottom wall were investigated using a 3D steady viscous computational fluid dynamics package with an unstructured grid. The heat transfer characteristics were studied as a function of the …

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Health Information Technology And Nurse Staff Efficiency: An Empirical Test In Residential Care Facilities, Jason D. Smith Jan 2012

Health Information Technology And Nurse Staff Efficiency: An Empirical Test In Residential Care Facilities, Jason D. Smith

Public Affairs Theses - Archive

This study examines the effects of health information technology (IT) on nursing staff efficiency. Specifically, the impact of clinical health IT applications on nursing staff efficiency is considered, along with the impact of health information exchange on nursing staff efficiency in those facilities with that utilize clinical IT. In an effort to elucidate these effects, I use data from the 2010 National Survey of Residential Care Facilities (NSRCF) to estimate six ordered logit models. The results indicate that clinical IT sophistication is positively associated with registered nurse (RN) HPPD. The effect on licensed practical nurses (LPN)/licensed vocational nurses (LVN) and …

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Spur Gear Analysis Using Mathcad, Jaydeep K. Panchal Jan 2012

Spur Gear Analysis Using Mathcad, Jaydeep K. Panchal

Mechanical and Aerospace Engineering Theses - Archive

In gear manufacturing applications, it is required to calculate surface stress and bending stress with minimum error. This thesis represents engineering calculation of bending and surface compression of external teethed involute spur gear. One may change the input values to calculate the engineering data for gears. The freedom of changing input values gives the capability to program to calculate for factor, Y; and the bending geometry factor, J to analyze spur gear geometry. Here the engineering gear calculation has been done by developing program in Mathcad software. The program is designed to calculate surface and bending stress data by input …

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Torsional Analysis Of A Composite I-Beam, Vishal Mukesh Smita Sanghavi Jan 2012

Torsional Analysis Of A Composite I-Beam, Vishal Mukesh Smita Sanghavi

Mechanical and Aerospace Engineering Theses - Archive

A simple methodology for analysis of thin walled composite I-Beam subjected to free torsion and restrained torsion is developed. Classical Lamination Theory is extended from the laminate level to the structural level for analysis purpose.The developed expressions for shear center, equivalent torsional rigidity and equivalent warping rigidity for a composite mono-symmetric I-Beam depends on the material properties, ply stacking sequence, fiber orientation and geometryThe results from the proposed theory gives better agreement with the ANSYSTM results than the traditional smeared property approach.

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The Nonprofit Sector's Involvement In Prisoner Reentry : A Mixed Methods Analysis, Michael Jay Woods Jan 2012

The Nonprofit Sector's Involvement In Prisoner Reentry : A Mixed Methods Analysis, Michael Jay Woods

Public Affairs Theses - Archive

The 1990's were plagued with crime and high recidivism rates, and the State of Texas responded by embarking upon the largest expansion of a criminal justice system in its history. Having served their sentences, record numbers of offenders who were sent to prison in the 1990's are now flooding the streets. At the time of their release, some of these offenders will have unmet needs, such as a lack of food, housing, and clothing. Others may need help enrolling in school or finding a job. Whatever their needs, a host of nonprofit organizations stand ready to assist ex-offenders in their …

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Control Of A Teleoperating Robotic Arm Subject To Time Delays, Pankaj Prakash Sarda Jan 2012

Control Of A Teleoperating Robotic Arm Subject To Time Delays, Pankaj Prakash Sarda

Mechanical and Aerospace Engineering Theses - Archive

Robotics in Minimally Invasive Surgeries (MIS) can be explored to its full potential if there is complete transparency between the surgeon and the virtual environment. In the setup, haptic device which conveys force from the surgeon to the surgery site and vice verse acts as the master station and robotic arm at the surgery site acts as the slave robot. In surgeries carried out remotely, time delays in the communication channels can cause commanded velocity/force to overshoot before the surgeon can even pull out during a task causing temporary or permanent damage during the surgery. Since the physical capability of …

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The Issue Of Governance In Neighborhood Planning Programs, Brian Price Jan 2012

The Issue Of Governance In Neighborhood Planning Programs, Brian Price

Public Affairs Theses - Archive

Neighborhood planning programs are a kind of initiative cities all across the country utilize to engage communities in planning processes affecting their own neighborhoods and to target resources and city initiatives within these spaces more effectively. These programs also represent a governance process, where publically relevant affairs are regulated at the interface of public, private, and civic sectors. Because these programs are highly variable between cities and are structured based off of local needs, trends, and agendas exploring governance contexts and relations at the urban and neighborhood level is helpful for explaining these differences in program goals and outcomes. At …

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Creating A Cohesive Triple Bottom Line: Helping The Urban Planner As A Liaison To The Citizen, Jeffery Earl Bell Jan 2012

Creating A Cohesive Triple Bottom Line: Helping The Urban Planner As A Liaison To The Citizen, Jeffery Earl Bell

Public Affairs Theses - Archive

This thesis is an attempt to create a viable liaison tool for the urban planner to create a cohesive idea of the Triple Bottom Line of sustainability between the citizen and the government of the city. By using consistent policy standards and adequate focus upon the new ideas of a sustainable lifestyle, the city should be able to create a viable structure for the future. In order to create a viable Triple Bottom Line, the citizen and the government will need to combine long term planning with current policy and standards of use and compliance in order to dedicate a …

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Study Of The Surface Roughness Evolution In Fatigued 316l Stainless Steel, Ye Wang Jan 2012

Study Of The Surface Roughness Evolution In Fatigued 316l Stainless Steel, Ye Wang

Mechanical and Aerospace Engineering Theses - Archive

Fatigue is a critical design consideration in many aerospace structures. As improvements are sought in overall performance, maintenance requirements, and total service life of modern aircrafts, the demands for fatigue control techniques, such as material design for fatigue resistance, reliable fatigue life prediction, and continuous material damage monitoring, have increased. The most common practices to ensure fatigue safety include: fracture mechanics based fatigue life prediction, periodic non-destructive inspections, and material processing control. Reasonable successes have been achieved by applying these three techniques to ensure the safe operation of aerospace structures. It is worth mentioning that most of the present fatigue …

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