Engineering Commons^™

Computational Aerodynamic Analysis Of Converging Free Jets, George Wayman Hatcher

Masters Theses

The aerodynamics of converging free jets was studied to determine the characteristics of the flow field involved in the manufacture of meltblown fibers. The two-dimensional computational fluid dynamic analysis was validated through comparison to boundary layer theory. The converging jet geometry consisted of two symmetric rectangular channels 30º from the axis of symmetry, 0.013 inches wide, converging toward a free expansion region at standard atmospheric conditions. The two channels were 0.015 inches apart at the exit, and the perpendicular wall region between them was flush with the upper and lower plate faces of the meltblowing die. Upstream boundary conditions of …

Rf Cmos Receiver Front-End Using A Reflex Amplifier, Radovan Kuzet

Theses and Dissertations - UTB/UTPA

A concept for an RF-CMOS receiver with reflex topology is developed and tested, using OrCad as the primary design and simulation tool. The main idea of the reflex topology is to reuse a Low Noise Amplifier (LNA) stage in the circuit and thus eliminate one high power consumption stage. A Gilbert cell is used for down conversion, with the benefit of low noise and low power while maintaining gain. A set of passive diplexers allows reuse of the LNA at the RF and IF. The complete circuit was simulated using 0.18 micron and 0.5 micron AMI technology. Parameters for the …

Effect Of Coating Additives On The Rheological And Optical Properties Of Coated Papers, Burak Aksoy

Dissertations

Although additives are used in small amounts (below 2wt.% of the total solids) in a coating formulation, they play an important role in the runnability and end-use performance of the coating. Among coating additives, the use of insolubilizers and fluorescent whitening agents (FWA's) has increased due to theincrease in demand for higher quality graphic papers and packaging. Zirconium containing insolubilizers were studied for their rheological effects on silica ink jet coatings. Both zirconium species had an influence on the theological properties of the coating and its components. The interactions between thezirconium salts and the coating were found to be weak …

Integration Of Lean Manufacturing And Value Engineering Techniques To Improve The Internal Distribution System In A Manufacturing Company, Sripadjaraj Prahladaraj

Masters Theses and Doctoral Dissertations

The XYZ Corporation is located in Lafayette, Georgia. The company produces cooking ranges for the North American market. It has 1500 employees with a daily production capacity of 1000 to 1500 cooking ranges. The company is implementing lean manufacturing techniques to improve their performance. One of their projects is to develop a distribution system, which will help in streamlining the internal distribution of Very High Pressure (VHP) adhesive tapes. The aim of this research is to develop a lean distribution system by applying techniques of lean manufacturing systems. To understand the existing process of distribution, a flow diagram was created. …

Fumed Metallic Oxides And Conventional Pigments For Glossy Inkjet Paper, Hyunkook Lee

Dissertations

Product development activity in the area of inkjet printing papers has accelerated greatly to meet the rapidly growing market for inkjet papers. Advancements in inkjet printing technology have also placed new demands on the paper substrate due to faster printing rates, greater resolution through increased drop volumes, and colorants added to the ink. To meet these requirements, papermakers are turning to pigmented size press formulations or pigmented coating systems. For inkjet coating applications, both the internal porosity of the pigment particles as well as the packing porosity of the coating affect print quality and dry time. Pores between the pigment …

Modeling The Strategic Impact Of Management Accounting Methods On The Implementation Of Lean Manufacturing, David Joseph Meade

Dissertations

This study examines the impact from the adaptation of lean manufacturing strategies on key external financial performance measures as reported by a number of management accounting methods. The research is not concerned with creating a justification for lean manufacturing strategies but rather it evaluates the inadequacies of standard financial reporting methods to accurately reflect operational improvements possible in the key performance measures through the early stages of a lean program.

ProModel simulation software is used in conjunction with Microsoft Excel and Visual Basic to create a simulated repetitive manufacturing environment and production planning and control system. The study examines the …

Lean Nox Trap Catalysis For Lean Burn Natural Gas Engines, Aaron Michael Williams

Masters Theses

As the nation’s demand for energy grows along with concern for the environment, there is a pressing need for cleaner, more efficient forms of energy. The internal combustion engine is well established as one of the most reliable forms of power production. They are commercially available in power ranges from 0.5 kW to 6.5 MW, which make them suitable for a wide range of distributed power applications from small scale residential to large scale industrial. In addition, alternative fuels with domestic abundance, such as natural gas, can play a key role in weaning our nations dependence on foreign oil. Lean …

Microstrain Pattern Analysis Of The Canine Patellar Tendon Following A Tibial Plateau Leveling Osteotomy, Joshua Paul Stapleton

Masters Theses

This study investigates the change in strain patterns of the canine patellar tendon following a Tibial Plateau Leveling Osteotomy (TPLO). The TPLO is a procedure used to minimize anterior tibial translation in canines following a cranial cruciate rupture. A noted clinical deficiency randomly seen with the TPLO is an inflammation of the patellar tendon. In some instances, the inflammation results in material damage resulting in a calcification of the tendon and in worst cases, a fracture of the patella.

In order to investigate the strain patterns, four fresh frozen canine cadaver stifles were used. The cadavers were mounted for stabilization …

Stress Corrosion Cracking Resistance Of Martensitic Stainless Steels For Transmutation Applications, Phani P. Gudipati

UNLV Theses, Dissertations, Professional Papers, and Capstones

The susceptibility of Alloy EP-823 to stress corrosion cracking has been evaluated using smooth and notched cylindrical specimens in neutral and acidic solutions at ambient and elevated temperatures using constant load and slow strain rate testing (SSR) techniques. C-ring and U-bend specimens have also been tested in the acidic solution. The effect of hydrogen on the cracking susceptibility has been evaluated under controlled cathodic potential. While no failures were observed with smooth specimens at constant load, the notched specimens showed failure. The SSR test results indicate that the true failure stress (o'_f), time to failure and ductility parameters …

Cfd Analysis Of 3-D Thermalhydraulics Flow Effects On Wall Concentration Gradient Profiles For Lbe Loop Fittings, Narain Armbya

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of the thesis is to study the effects of thermalhydraulics flows on the wall concentration gradient profiles in LBE loop fittings. To that end detailed models of the fittings have been constructed to study these effects. These fittings include sudden expansion, sudden contraction, t-joint and elbow. The typical flow rates chosen for these simulations are typical of design criteria chosen for the loop with Reynolds numbers expected around 200,000 and the usual axial temperature profiles which are being characterized in the DELTA loop at LANL. STAR-CD is the simulation package used to make these predictions, which include detailed …

Retrieval Of Nano-Size Particles From A Solid Substrate, Krishna Prasad Podila

Masters Theses

The retrieval of nano-size particles from suspects and crime scenes can significantly enhance surveillance and crime investigation. The Thesis deals with extensive study of free surface energy coupled with Hertzian contact energy under different conditions between a nano-sized particle and a substrate and the various methods of dislodging the particle. Using the Johnson-Kendall-Roberts (JKR) theory, a physical spring-mass-damper model is defined. Mathematical equations are formulated and solved with non-linear equations simulating the real world situation. Using Newmark’s β method, the system is solved for response of free and forced vibrations taking moisture to be responsible for damping. Key assumptions such …

Stress Corrosion Cracking And Hydrogen Embrittlement Of Martensitic Alloy Ep-823, Mohammad K. Hossain

UNLV Theses, Dissertations, Professional Papers, and Capstones

This investigation is focused on the evaluation of stress corrosion cracking (SCC), localized corrosion, and hydrogen embrittlement (HE) susceptibility of martensitic Alloy EP-823 in neutral and acidic solutions at ambient and elevated temperatures. While no failures were observed in smooth specimens in the neutral solution, failures were noticed in the 90°C acidic solution at constant-load (CL) leading to a threshold stress (O'_th) of 102 ksi. The presence of a notch reduced the O'_th value to 91 ksi in a similar environment. The ductility (%El and %RA), time-to-failure (TTF), and true failure stress (O'_r) were gradually …

Environment Assisted Cracking Of Target Structural Materials Under Different Loading Conditions, Venkataramakrishnan Selvaraj

UNLV Theses, Dissertations, Professional Papers, and Capstones

Martensitic Alloy HT-9 has been tested for its evaluation of stress corrosion cracking resistance in neutral and acidic solutions at ambient and elevated temperatures incorporating smooth and notched cylindrical specimens under constant load and slow strain rate (SSR) conditions. C-ring and U-bend specimens have also been tested for stress corrosion cracking evaluation in the acidic solution. The role of hydrogen on the cracking tendency has been evaluated by cathodic applied potential.

The results of constant load testing enabled the determination of the threshold stress for stress corrosion cracking in susceptible environments. The magnitudes of ductility parameters were reduced with increasing …

Stabilization Of Desert Sand Using Water-Borne Polymers, Shihab Wagiealla Abdalla Mohamed

Theses

Soil stabilization is one of the various applications that have benefited from the advances in polymeric materials. In this research, three water-borne polymeric emulsions with different chemical and physical properties were tested as stabilizers for sandy soil.

This study is divided into three parts. In the first part, the performance of the three emulsions in reducing the hydraulic conductivity and improving the mechanical properties of the sand was investigated. Specimens with polymer contents of up to 2 wt. % were prepared using two preparation methods, mixing and spraying. Both types of specimens exhibited a significant improvement in the studied properties. …

Ab Initio Calculation Of Electronic And Optical Properties Of Beryllium Chalcogenides (Bes, Bese, And Bete) Under The Effect Of Pressure, Aisha Ali Saif Bannan Al-Kaabi

Theses

There are several methods for materials simulation. Ab initio or first principles methods are used to solve the quantum mechanical equation which govern the behavior of a system. Ab initio calculation of the optical and electronic properties of solids is fundamental in solid state physics. APW+lo is used to examine different properties of BeS, BeSe and BeTe. Beryllium compounds show different features in structure under different pressures, and they also show a phase transition from Zinc blende to Hexagonal transitions in II-VI semiconductors. Little is known about the ground state properties of Beryllium Chalcogenides. The aim of this work is …

Consistency Results For The Roc Curves Of Fused Classifiers, Kristopher S. Bjerkaas

Theses and Dissertations

The U.S. Air Force is researching the fusion of multiple classifiers. Given a finite collection of classifiers to be fused, one seeks a new classifier with improved performance. An established performance quantifier is the Receiver Operating Characteristic (ROC) curve, which allows one to view the probability of detection versus the probability of false alarm in one graph. Previous research shows that one does not have to perform tests to determine the ROC curve of this new fused classifier. If the ROC curve for each individual classifier has been determined, then formulas for the ROC curve of the fused classifier exist …

Non-Cooperative Detection Of Ultra Wideband Signals, Brett D. Gronholz

Theses and Dissertations

Techniques for the non-cooperative (non-matched filter) detection of impulse-like ultra wideband signals using channelized receiver architectures are developed and evaluated. Each technique considered is modeled and simulations conducted to characterize detection performance, the results of which are compared with the detection performance of three receivers: the matched filter receiver, which provides optimum detection performance in AWGN; the radiometer, or energy detector; and the multi-aperture cross correlation receiver. It is shown that a channelized receiver (with no downconversion) can provide approximately 2.5 dB improvement over the radiometer when performing detection using the temporal-temporal matrix (TTM). The TTM processing technique provides the …

Understanding And Improving Moment Method Scattering Solutions, Clayton Paul Davis

Theses and Dissertations

The accuracy of moment method solutions to electromagnetic scattering problems has been studied by many researchers. Error bounds for the moment method have been obtained in terms of Sobolev norms of the current solution. Motivated by the historical origins of Sobolev spaces as energy spaces, it is shown that the Sobolev norm used in these bounds is equivalent to the forward scattering amplitude, for the case of 2D scattering from a PEC circular cylinder. A slightly weaker relationship is obtained for 3D scattering from a PEC sphere. These results provide a physical meaning for abstract solution error bounds in terms …

Introduction To Mechanical Engineering, Lorik Abdullai, Joseph R. Dunn

Honors Theses

I can still remember back in high school when I was faced with a decision thousands of students experience every year: What college was I going to choose, and what major was I going to study? It seemed like every time I saw friends and relatives they asked me that question. Meanwhile, I knew that going to a major university would give me more choices in case I changed majors. As it turned out, Western Michigan University was the best package for me when I considered the financial aid, the program ofmy major, location of the university, and its friendly …

Telerobotic Controller, Michael Fewless, George Slater, Steve Waldron

Honors Theses

Atelerobotic system allows a user to interact with an environment indirectly. Our project successfully creates a telerobotic environment between the Phantom 1.5 controller and the UMI RTX robotic arm. Utilizing the haptic features of the Phantom controller, a more realistic interaction was created between the telerobotic system and the user by providing sensory feedback. As the user manipulates the hand-controlled Phantom device, signals are sent via a parallel port to the personal computer. A real-time WIN32 application, utilizing the GHOST SDK library, reads the position of the Phantom controller's coordinates and calculates the corresponding motor positions of the UMI RTXrobotic …

Design Of Cmos Four-Quadrant Gilbert Cell Multiplier Circuits In Weak And Moderate Inversion, Craig Timothy Remund

Theses and Dissertations

This thesis presents four-quadrant CMOS current-mode multiplier architectures based on the bipolar Gilbert cell multiplier architecture. Multipliers are designed using the CMOS subthreshold region to take advantage of the subthreshold exponential I-V relationship that closely matches bipolar modeling. It is discovered that biasing to remove drift current components and to address higher order effects such as ideality factor mismatch, threshold mismatch, body effect, and short channel effects, is important to provide a linear multiplier. It is also shown that distortion caused by device size mismatch and offset input currents can be used to cancel the distortion introduced by drift currents …

Development Of Pole Impact Testing At Multiple Vehicle Side Locations As Applied To The Ford Taurus Structural Platform, Mark Halford Warner

Theses and Dissertations

A test method was developed whereby repeated pole impacts could be performed at multiple locations per test vehicle, allowing a comparison of energy and crush relationships. Testing was performed on vehicles moving laterally into a 12.75 inch diameter rigid pole barrier. Crush energy absorption characteristics at the different locations were analyzed, and the results compared to test data from broad moving barrier crashes and available crash tests with similar pole impacts. The research documents the crush stiffness characteristics for narrow impacts at various points on the side of the Taurus vehicle platform. Factors encountered during the research include the importance …

The Effectiveness Of Computer-Based Tutorials In Learning Computer-Aided Design Methods For Tool Design Procedures, Andrew Moroni Hall

Theses and Dissertations

Throughout the past twenty-five years the process of designing and manufacturing a product has been revolutionized by the integration of Computer Aided Design (CAD). Although three-dimensional solid modeling, or 3-D CAD offers a better representation of the product in a virtual environment, it can be complicated and difficult to learn. Tutorials have been developed to assist manufacturing tool design student in the learning of 3-D CAD principles as they apply to tool design. This study seeks to test the effectiveness of those tutorials. A BYU tool design class was divided into two groups according to their assigned laboratory time. The …

Polarimetric Temperature Sensor Using Core-Replaced Fiber, Benjamin L. Ipson

Theses and Dissertations

Optical fibers are increasingly being used to create sensing devices. The D-fiber has an elliptical core and exhibits birefringence. This birefringence can be used to create a polarimetric sensor. The elliptical core supports two orthogonal modes that have separate effective indices of refraction. The indices of refraction change with a change in temperature. Since the effective indices of refraction change differently for the two modes, the birefringence also changes. This change in birefringence can be seen as a change in detected power through the fiber through the use of polarizers. The fiber then becomes a temperature sensor. The sensitivity of …

Compliant Mechanisms To Perform Bearing And Spring Function In High Precision Applications, Jesse R. Cannon

Theses and Dissertations

An increasing number of mechanical systems are being designed on the micro and meso scales. Assembly and maintenance become increasingly difficult as the size of mechanisms decrease, and the minimum size of traditional elements such as bearings and springs is limited. The backlash of bearings also limits their usefulness in applications where high precision and repeatability are needed. At small scales and for high precision applications, alternative, non-traditional elements are needed.

The objective of this thesis is to develop reliable and scalable compliant components to replace bearings and helical springs. Components replacing springs must be able to produce specified torque/motion …

Improved Signal Integrity In Ieee 1149.1 Boundary Scan Designs, Efren De Jesus Rangel Taboada

Theses and Dissertations

This work is an analysis of solutions to problems derived from inherent timing and signal integrity issues in the use and application of the IEEE 1149.1 Standard at the board level in conjunction with its test system. Setup or hold times violations may occur in a boundary scan chain using IEEE 1149.1 compliant devices. A practical study of the TDI-TDO scan data path has been conducted to show where problems may arise in relationship to a particular board topology and test system. This work points to differences between passing and failing scan path tests for problem characterization. Serial data flow …

Thermally Developing Electro-Osmotic Convection In Circular Microchannels, Spencer L. Broderick

Theses and Dissertations

Thermally developing, electro-osmotically generated flow has been analyzed for a circular microtube under imposed constant wall temperature (CWT) and constant wall heat flux (CHF) boundary conditions. Established by a voltage potential gradient along the length of the microtube, the hydrodynamics of such a flow dictate either a slug flow velocity profile (under conditions of large tube radius-to-Debye length ratio, a/lambda_d) or a family of electro-osmotic flow (EOF) velocity profiles that depend on a/lambda_d. The imposed voltage gradient results in Joule heating in the fluid with an associated volumetric source of energy. For this scenario coupled with a slug flow velocity …

Analysis Of Power Takeoff Shafts To Prevent Injuries/Fatalities, Naomi Bronson

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science and Technology at Morehead State University in partial fulfillment of the requirement for the Degree of Master of Science by Naomi Bronson on November 1, 2004.

Quantifying The Effects Of Aging On The Mechanical Properties Of Medical Grade Polycarbonate And Uv Cured Adhesives, Christopher James Lewis

Theses and Dissertations

Advances in engineering polymer technology have created a generation of high strength-to-weight materials for medical applications, with virtually no adverse interactions with body fluids. Polycarbonate is a widely used engineering polymer, and is often used in connection with ultra-violet light (UV) cured adhesives. Because of the chemical complexity of polymers, little is known about their actual aging characteristics. By characterizing the effects of aging, storage environment, and sterilization on medical grade polycarbonate/adhesive system properties, more accurate failure predictions can be made. In this thesis, efforts to better understand the effects of accelerated aging on a medical grade polycarbonate and UV …

A Cad-Centric Approach To Cfd Analysis With Discrete Features, Matthew Lee King

Theses and Dissertations

During the conceptual design stage several concepts are generated, and a few are selected for detailed analyses. CAD models from conceptual design often follow the "over-the-wall" approach for downstream analyses such as FEA, CFD, heat transfer, and vibrations. A CAD-centric approach will be applied to the CAD-to-CFD process to help industry in an ongoing quest to shorten the design cycle time. The CAD-centric approach consists of using the CAD model as a source of data for downstream applications such as mesh generation, and CFD setup. The CAD model used in the CAD-centric approach contains the geometry to be analyzed and …