Engineering Commons^™

A K-Epsilon Extension For Wall-Bounded Flows On The Broadband Aeroacoustic System Simulator, David González

Masters Theses

The turbulence modeling capabilities of the Broadband Aeroacoustic System Simulator (BASS), an experimental code developed at NASA Glenn Research Center, have been extended to include wall-bounded flow capabilities. This was done by first validating the code's viscous solving routines by comparing numerical solutions to known, simple analytic solutions. Finally, the dynamics of the wall shear flows were accounted for with the use of wall-damping functions incorporated into the turbulence model. The results for both viscous and turbulence routines agree well with published data.

Simulating Discriminatory Profiling, Oscar Neal

Masters Theses

There is a concern that racial profiling is being used to invoke searches and stops in spite of its violation of the fourth amendment. Simulation methods are used to study the correlation test of stops, searches and citations with race, age, and gender. The design uses sensitivity analysis of inputs to determine their relationship to outputs statistics of a police department's citations and stops. Experimental results are than used to verify and predict departmental bias. A simulation program written in Visual Basic is used as a tool to explore simulation techniques. A formulation of simulation uses in studying discriminatory profiling …

Evaluation Of Mechanical Properties Of Recycled Aggregate Concrete, Sajjad Ali Khan

Masters Theses

The maintenance and repair work in the civil engineering infrastructures develops the production of huge wastes which causes the growth of waste piles, additional costs in construction projects and some environmental problems. If this waste is recycled and used again in construction projects, it will help to overcome the problems discussed earlier. Moreover, if natural aggregates are supplemented by recycled aggregate, it will preserve the natural resources and also put a pause in the deterioration of natural landscape.

This thesis addresses the importance of using recycled aggregate in concrete structures. Its practical feasibility in construction projects is studied in light …

Mixing Flow Structures Of Scalloped, Forced Lobed Mixers Using Piv And Plif Measuring Techniques, Nathan J. Cooper

Masters Theses

An Experimental study of internal forced lobed mixers similar to those used in jet aircraft engines is performed using whole field species concentration and velocity measuring techniques. Planar temperature and velocity measurements using Planar Laser Induced Fluorescence (PLIF) and 2D Particle Image Velocimetry (PIV) are performed for lobed, lobed scalloped and splitter mixers in aqueous solution. Specific emphasis is given to study scallops or notches cut into the mixer trailing edge and their role in mixing enhancement. Mixing is compared through velocity and species concentration measurements on axial and streamwise planes for the three dimensional, forced mixers in a confined …

Evaluation Of Mechanical Properties Of Self-Consolidating Concrete, Bhusan Basnet

Masters Theses

The concept of Self-Consolidating Concrete is a fresh and rapidly ramping technology in USA, but in some other continents such as Japan and Europe it is in fully fledged stage. The development of this technology has a high potential to economize construction minimizing labor, scheduled time and equipment eliminating consolidation process. In USA, construction professionals are reluctant to its in-effect application because of lack of deliberate and methodological steps for production and applications. The lack of study of its durability characteristics and confusion in design and production process are seems to be vital factors hindering full scale production and application …

Ductile Regime Nano-Machining Of Silicon Carbide, Biswarup Bhattacharya

Masters Theses

This thesis describes experimental work carried out to study the ability to ductile . single point diamond turn both polycrystal Silicon Carbide (SiC) and chemically vapor deposited (CVD) SiC. A Precitech diamond turning machine was used for ductile regime machining of polycrystal SiC at depths of 10 and 25 nm. The possibility of machining SiC in the ductile mode was substantiated by post process analysis of the chips collected during machining and the surface profiles. The force data obtained during machining was recorded and compared later with the different depth of cuts. An investigation into the ability to single point …

Determination Of Stiffness Matrix Of Tapered Roller Bearings For Vibration Models, Jeeva Kumar

Masters Theses

The stiffness matrix of tapered roller bearings under radial and axial load conditions was evaluated using an analytical model and an experimental approach. An experimental test system was designed and manufactured to determine the radial stiffness of the bearing under combined axial and radial load conditions. A second fixture was designed to measure the stiffness of the bearing under pure axial load conditions. The stiffness coefficients determined have been compared with those obtained from the analytical model, OEM (Original Equipment Manufacturer) data and ABAQUS model (finite element analysis software).

Guidelines To Select A Computerized Maintenance Management System, Dattaraj Kamalapurkar

Masters Theses

In today's highly competitive global economy, maintenance personnel are presented with more difficult challenges than at any previous point in time. In order to meet these challenges, many maintenance managers tend to rely . on Computerized Maintenance Management System (CMMS). When properly selected and implemented, CMMS is one of the most powerful cost reduction tools in any organization. However in reality, many CMMS implementations fail rather than achieve success. While there are many contributing factors, one major factor that greatly impacts successful implementation is selecting the right CMMS system. With more than 200 CMMS systems to choose from, selecting the …

Capacitated And Uncapacitated Facilities Locationallocation Problem With Sensitive Prices, Stochastic Demands, And Inventory, Yaser Al-Alawi

Dissertations

This study developed a quantitative model that solves a facility locationallocation (LA) problem that maximizes the net profits generated from expected sales. The model was formulated to take into consideration demand uncertainty, sensitive prices, and existence of inventory for capacitated and uncapacitated facilities. Four new models for the LA problem with stochastic demands and inventory were developed and studied. The four models were combinations of capacitated and uncapacitated facilities and sensitive and insensitive prices.

A new method was proposed for achieving optimality, and an approximation procedure was developed that could find near-optimal solutions for problems that could not be solved …

Inertial Navigation System, Michael Calabrese Jr., David Engblom, Aaron Fleckenstein

Honors Theses

Accelerometer-based inertial navigation systems present an inexpensive alternative to gyroscope and global positioning navigation systems. An array of accelerometers comprises the basic design of the inertial navigation system. The position of the device can be continuously updated based on the previous device location and measurements of the device acceleration. There are fewer moving parts in an accelerometer-based system than in a gyroscopic device, and it is free of the earth bound constraints of a global positioning system. The prototype wirelessly interfaces with a data-collection system, which processes the data and provides a graphical display of the trajectory traveled.

Two accelerometer …

Design Of A Reconfigurable State Transition Algorithm For Fuzzy Automata, Paolo A. Tamayo

Masters Theses

An Ontological Controller, a type of supervisory controller used for complex industrial systems, is usually characterized by a large global state set. Monitoring the global state set of these systems is impractical when the desired goal path is chosen since the decision on the next state depends only on a small section of the total state space. The approach is to operate only in a small moving window of the large state transition path. The Hybrid Fuzzy-Boolean Finite State Machine (HFB-FSM) is part of the solution to implement this scheme. The HFB-FSM models the state graph along with plant data …

Alkali Silica Reaction In Virgin And Recycles Aggregates: State Of The Art And Experimental Investigation Using Astm C 1260 And The Staining Method, Shadi Sami Bajjali

Masters Theses

Alkali silica reaction (ASR) is one of the most prevalent causes of concrete deterioration worldwide. A study done in 1995 showing the impact of ASR on structures stated that 104 concrete dams and spillways, massive concrete structures, have been damaged by alkali silica reaction up to date. Since its discovery by Stanton (1940), there has been significant research on ASR, and major advances have been made in understanding the mechanism underlying ASR-induced expansion and in developing methods of preventing ASR in new and existing concrete through proper measures including proper materials selection and mixture proportioning.

This thesis summarizes the findings …

Load Interaction Effects On Fatigue Crack Growth, Stoyan Ivanov Stoychev

Dissertations

Load excursions, in the form of tensile and compressive overloads are known to produce interaction effects during subsequent constant amplitude loading. In this work, the fatigue crack growth and crack closure levels, under both constant amplitude and variable amplitude loading, are investigated in the aluminium-lithium alloy 2090-T84, and the aluminium alloys 2024-T351 and 7150-T651. The crack closure measurements were obtained using both a crack tip opening displacement (CTOD) gauge and a crack mouth opening displacement (CMOD) gauge.

Fatigue crack growth tests were performed on specimens of thickness 1.6mm, 3mm, 6mm and 14mm. Tests were performed at load ratios of 0.1 …

Segmentation Of Thermal Images For Non-Destructive Applications, Solange Yohali

Masters Theses

Infrared Thermogarphy (IR) is used in this project to detect subsurface conditions in concrete specimen for nondestructive testing and evaluations. This thesis goal is to bridge the gap between Infrared Testing and image analysis by developing an algorithm based on the region growing approach to segment the images and identify the voids without human interference or prior knowledge of the conditions. The segmentation algorithm starts with seed points as the hottest pixels in the image, and then regions are grown based on a neighborhood comparison criterion. The algorithm was tested on images collected from concrete specimen containing various man-made defects …

Prediction Of Shaft Vibration Modes In A Geared Transmission System, Kevin W. Marsh

Masters Theses

During the development process of heavy-duty truck transmissions, specific gear designs (geometries) are created to meet load requirements and ratio coverage. Few tools are available to investigate the noise generating potential of these transmissions early in the design stages. This research describes the development and application of a software program that predicts transmission countershaft vibration modes. From simple gear and shaft geometries, the program calculates gear mesh forces and bearing forces then construct the system of equations to compute the shaft vibration modes. Because of the way the input data was structured, this software tool can also be used to …

Stabilization Of Curtain Coater At High Speeds, Peeyush Tripathi

Dissertations

High-speed curtain coating is an emerging technology trying to gain commercial acceptance by the paper industry as a pre-metered and non-impact coating process. Curtain coating could offer enormous economic and process advantages over conventional coating methods due to non-impact and excellent coverageat reduced coat weights. Due to non-impact and non-contact type of coating operation, curtain coating can operate with fewer sheet breaks or the strength requirements of the base sheet can be greatly reduced. High speed curtain coating for commodity coated grades like LWC is still a challenge. Relationship between various process, basesheet and coating variables and their mechanism must …

The Detection Of Common Concrete Bridge Deck Defects Using The Thermography, Impact Echo, And Ground Penetrating Radar, Saleh Z. Nabulsi

Masters Theses

The transportation infrastructure in the United States is deteriorating and will require significant improvements. A recent report by the American Society of Civil Engineers (ASCE) gave an overall grading of D⁺ to the nation's infrastructure. Approximately 162,000 of the nation's bridges are structurally deficient or functionally obsolete. The total estimated cost to bring conditions to acceptable levels over the next two decades would exceed $1.9 trillion. Consequently, innovations in the area of transportation infrastructure maintenance and rehabilitation are key to the health and wellness of this valuable national asset.

A major component of maintenance and rehabilitation is the ability …

Experimental Determination Of Convection Boiling Curves For Water And Ethylene Glycol In A Rectangular Channel With Localized Heating, Andrew T. O'Neill

Masters Theses

Convective boiling experiments were conducted to show the effects of velocity, pressure, and subcooling on both water and a water-ethylene glycol mixture. Boiling curves were obtained in a 30 mm wide by 20 mm high rectangular channel with an upward facing 20 mm wide by 30 mm long rectangular copper heater. The velocity ranged from 0.5 m/s to 4.0 m/s, the pressure ranged from 1.0 atm to 2.6 atm, and the subcooling ranged from 10°C to 50°C. The curves were generated with measured heat fluxes up to 100W/cm² . The inlet conditions of temperature, velocity, and pressure were maintained …

Development Of A Statistical Model For Process Control To Eliminate Sink Marks In Injection Molded Products, Kurt Frederick Hayden

Masters Theses

Customer demands for high-quality, defect-free injection-molded products are ever increasing. In order to satisfy these quality requirements, much effort is spent monitoring and controlling variable data such as cycle time, part weight, and dimensions. Attribute defects such as sink or splay are often overlooked in the development of process control systems. However, customers reject products because of these attribute defects. Industrial control systems based upon process variables and product design variables can detect conditions that may result in the molding of products with attribute defects. The systems can then correct the process prior to the molding of these defective products. …

Tilt-Rotor Aircraft Flight Control Design With Pid, H2, H∞ And Μ Synthesis Approach, Yinyang Zhai

Masters Theses

The main objective of this project is to design optimal controllers for Hover and Cruise Dynamic Systems of XV-15 Tilt Rotor Aircraft. The design criterion is to make system Robust in sense of both Stability and Performance. μ synthesis is applied to system uncertainty; this method is less conservative as compared to the worst-case H_∞ synthesis. The power of P∆K architecture is to represent uncertainties and system interconnections in μ synthesis. For comparison, the classical control techniques, such as Root Locus Algorithm, PID controller design with ITAE Performance Index, and Pole Placement Approach are also investigated. For application of …

Decision Support System For Bridge Maintenance, Imran Fazal

Masters Theses

Three main problems that deteriorate bridge decks are cracking, delamination and corrosion. Once concrete bridge deck is infected with any of the three problems, it becomes susceptible to more serious structural and architectural problems. Corrosion, cracking and delamination sometimes occur in tandem in concrete bridge decks, which makes the situation even more worse.

Pontis, which has been successfully employed by various department of transportation is basically a network level BMS which prioritize bridges or groups of bridges for repair and rehabilitation funds. In this scenario researchers and scholars agree that along side Pontis certain other project specific BMS (Expert systems …

A Method For Classification Analysis On Simultaneous Product Defects, Jason S. Trahan

Masters Theses

There have been many advancements that share similar tools and techniques that help reduce the manufacture of nonconformities. These include computer-aided analysis, design reviews, total quality management, multivariate analysis, process monitoring and control, and root cause analysis to mention a few.

This work details the methodology developed for manufacturing companies to predict attribute defects. Injection molding was used to demonstrate the proposed methodology. Data were collected on a variety of tool design and construction attributes thought to affect the performance of a tool. The independent variables consisted of categorical and numerical data types. The dependent variable was a nominal four-tuple …