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Articles 2281 - 2310 of 2517

Full-Text Articles in Engineering

A Laboratory Study On The Effects Of Submerged Vertical And Semicircular Breakwaters On Near-Field Hydrodynamics And Morphodynamics, David Young May 2008

A Laboratory Study On The Effects Of Submerged Vertical And Semicircular Breakwaters On Near-Field Hydrodynamics And Morphodynamics, David Young

All Theses

A laboratory study is presented herein that investigates the effects of submerged vertical and semicircular breakwaters on near-field hydrodynamics and morphodynamics. Breakwaters are employed worldwide in order to reduce destructive wave forces often imparted on vulnerable shorelines; a task partially completed by reflecting incident wave energy back out to sea. However, two common side-effects of their function are the occurrence of scour at the breakwater, which can lead to structural problems; and offshore ripple formations, which are influential in scour protection failure and sediment transport patterns. This study aims to determine a relationship between breakwaters and the wave reflection coefficient …

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Real-Time Power Management Of A Fuel Cell/Ultracapacitor Hybrid, Wesley Greenwell May 2008

Real-Time Power Management Of A Fuel Cell/Ultracapacitor Hybrid, Wesley Greenwell

All Theses

This thesis presents the system architecture design, system integration methodology, and real-time control of a fuel cell/ultracapacitor hybrid power system. The main objective is for the hybrid system to respond to real-world fluctuations in power without negatively impacting fuel cell life.
A Proton Exchange Membrane (PEM) Fuel Cell is an electrochemical device which converts the chemical energy of pure hydrogen into electricity through a chemical reaction with oxygen. The high conversion efficiency, zero harmful emissions, high power-to-weight ratio, scalability, and low temperature operation make PEM fuel cells very attractive for stationary and portable power applications. However, fuel cells are limited …

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Development Of A Colorimetric Test For Quantification Of Uranium In Drinking Water, Amy Ratliff May 2008

Development Of A Colorimetric Test For Quantification Of Uranium In Drinking Water, Amy Ratliff

All Theses

A new method was developed for the determination of uranium in groundwater above 30µg/L (30ppb). This concentration is the maximum contaminant level (MCL) for uranium in drinking water, which was set in December 2003 by the US EPA under the provisions of the Safe Drinking Water Act. The method is rapid and requires little technical training to conduct, allowing it to be used by consumers, in the laboratory, or in the field. The two-step technique involves preconcentrating uranium using a U/TEVA-2 extraction chromatographic resin followed by complexation with a pyridylazo indicator dye, Br-PADAP. At neutral pH, a counter ion is …

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Geotechnical Investigations At Three Sites In The South Carolina Coastal Plain That Did Not Liquefy During The 1886 Charleston Earthquake, Ronald Boller May 2008

Geotechnical Investigations At Three Sites In The South Carolina Coastal Plain That Did Not Liquefy During The 1886 Charleston Earthquake, Ronald Boller

All Theses

Geotechnical investigations were performed at three sites in the South Carolina Coastal Plain where liquefaction is believed to not have occurred in 1886 or during other Holocene earthquakes. The three sites are the Coastal Research and Education Center (CREC) located near Charleston, and the Borrow Pit and Marsh Road sites at Hobcaw Barony near Georgetown. The investigations consisted of nine seismic cone penetration test (SCPT) soundings, three non-seismic cone penetration test (CPT) soundings, one standard penetration test (SPT) boring, and two dilatometer test (DMT) soundings. Shear wave velocities (Vs) were calculated from the SCPTs using pseudo interval measurements at the …

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Hypoelastic Modeling Of Reinforced Concrete Walls, Mohsen A. Shayanfar, Amir Safiey May 2008

Hypoelastic Modeling Of Reinforced Concrete Walls, Mohsen A. Shayanfar, Amir Safiey

Publications

This paper presents a new hypoelasticity model which was implemented in a nonlinear finite element formulation to analyze reinforced concrete (RC) structures. The model includes a new hypoelasticity constitutive relationship utilizing the rotation of material axis through successive iterations. The model can account for high nonlinearity of the stress-strain behavior of the concrete in the pre-peak regime, the softening behavior of the concrete in the post-peak regime and the irrecoverable volume dilatation at high levels of compressive load. This research introduces the modified version of the common application orthotropic stress-strain relation developed by Darwin and Pecknold. It is endeavored not …

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Computational Method For Solving Spoke Dynamics On High Speed Rolling Tweel, Kranti Kiran Manga May 2008

Computational Method For Solving Spoke Dynamics On High Speed Rolling Tweel, Kranti Kiran Manga

All Theses

Extensive studies have been conducted in the past to show that the characteristics of a non-pneumatic structure, the TweelTM are the same as the pneumatic tires. These characteristics include low contact pressure, low stiffness, low energy loss from obstacle impacts, low mass, and high load-carrying capacity. The TweelTM consists of a ring shaped shear beam comprised of two inextensible membranes separated by a relatively low modulus elastic material. This shear beam is connected to the hub by thin elastic spokes.
When used for high speed rolling applications, the TweelTM produces unacceptably high levels of acoustic noise. It has been suggested …

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Renewable Resource Lactide Derived Materials: Scaled-Up Synthesis, Characterization And Applications, Akhilesh Singh May 2008

Renewable Resource Lactide Derived Materials: Scaled-Up Synthesis, Characterization And Applications, Akhilesh Singh

All Dissertations

Renewable resource monomer, lactide, derived copolymers and terpolymers were synthesized on a few hundred gram scale with specialty/commodity co-monomers such as perfluoropolyether and bisphenol A derivatives. The modifications resulted in improved properties such as surface energy, crystallization, and glass transition temperature of the polylactide.
Ring-opening polymerizations of L-lactide were performed using different block length perfluoropolyethers as macro-initiators and tin octoate as the catalyst. The resultant polylactide-perfluoropolyether-polylactide block copolymers were characterized by various analytical and microscopic techniques such as differential scanning calorimetry, thermogravimetric analysis, nuclear magnetic resonance spectroscopy, dynamic mechanical analysis, wide-angle x-ray diffraction spectroscopy, polarized optical microscopy, etc.
The incorporation …

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Biodiesel Production From High Free Fatty Acid Content Feedstocks, Kaewta Suwannakarn May 2008

Biodiesel Production From High Free Fatty Acid Content Feedstocks, Kaewta Suwannakarn

All Dissertations

Biomass, such as animal fats and grease, is one of the better sources for transportation fuels, e.g. biodiesel. Use of such biomass in the biodiesel synthesis decreases the need for fossil energy, provides an outlet for utilizing the abundant resources effectively and economically, results in a cleaner fuel that is biodegradable, renewable, and non-toxic. Free fatty acid (FFA) esterification and triglyceride (TG) transesterification with low molecular weight alcohols are the central reactions for the biodiesel production. The focus of this research is to establish a better fundamental insight into heterogeneous catalysis for biodiesel forming reactions, in an attempt to design …

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Random Road Analysis And Improved Gear Ratio Selection Of A Front Wheel Drive Drag Racing Car, Thomas New May 2008

Random Road Analysis And Improved Gear Ratio Selection Of A Front Wheel Drive Drag Racing Car, Thomas New

All Theses

Drag racing has been around since the 1950's and has become a very popular and very competitive sport. The difference between winning and losing can be hundredths and even thousandths of a second. Drag racing teams need every advantage they can get in order to excel in their field. On-track testing is very expensive and can consume large amounts of time and resources that a race team may not be able to afford.
One way to address this potential problem of high cost is by using computer simulation to show how your drag race car may perform at different tracks …

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Immobilization Of Biomolecules On Polymer Scaffolds: A Novel Approach, Joshua Barringer May 2008

Immobilization Of Biomolecules On Polymer Scaffolds: A Novel Approach, Joshua Barringer

All Theses

In this thesis, I describe the successful development of a procedure for the step-by-step formation of a multi-layer polymer scaffold on a silicon wafer and the characterization of these materials. Also discussed is the development of a procedure for the non-site specific attachment of a biomolecule to the modified silicon wafer, including scaffolds modified via drop-on-demand, DOD, inkjet printing. Ellipsometry, x-ray photoelectron spectroscopy (XPS), FTIR, fluorometry, and static water contact angle measurements are used to study the nanoscale structure and properties of the interfacial, thin film-modified surfaces. Polymers based on 2-vinyl-4,4-dimethylazlactone (VDMA) are used as the platform onto which biomolecules …

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Analysis And Experiments For Tendril-Type Robots, Lara Cowan May 2008

Analysis And Experiments For Tendril-Type Robots, Lara Cowan

All Theses

New models for the Tendril continuous backbone robot, and other similarly constructed robots, are introduced and expanded upon in this thesis. The ability of the application of geometric models to result in more precise control of the Tendril manipulator is evaluated on a Tendril prototype. We examine key issues underlying the design and operation of 'soft' robots featuring continuous body ('continuum') elements. Inspiration from nature is used to develop new methods of operation for continuum robots. These new methods of operation are tested in experiments to evaluate their effectiveness and potential.

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Ductile-Regime Machining Of Glass Using The Micromilling Process, Kevin Foy May 2008

Ductile-Regime Machining Of Glass Using The Micromilling Process, Kevin Foy

All Theses

Glass is a homogeneous material with amorphous crystal structure that is produced through the rapid cooling of its molten state below the glass transition temperature. Glass exhibits many excellent mechanical and physical properties, and it is widely used in automotive, communications, optics, electronics, architectural, and biomedical industries. For certain applications such as DNA microarrays, glass components with microfeatures are typically produced using a combination of photolithography and etching processes, which is generally time consuming and can involve hazardous chemicals. It would be ideal to fabricate some glass devices through mechanical micromachining for some rapid prototyping applications of glass-based devices, but …

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Storm Water Export Of Nitrogen, Phosphorous, And Carbon From Developing Catchments In The Upper Piedmont Physiographic Province, Laura Reid May 2008

Storm Water Export Of Nitrogen, Phosphorous, And Carbon From Developing Catchments In The Upper Piedmont Physiographic Province, Laura Reid

All Theses

Impacts on water quality caused by land use change from forests and pastures to housing subdivisions were evaluated in catchments undergoing active development in the upper Piedmont physiographic province of South Carolina. Specific attention was focused on the export of nitrogen, phosphorus and carbon from these catchments during storm events. Three catchments with varying stages of development were compared to categorize the effects of land disturbance. Storm events occurring within a four year period of 2004 through 2007 were studied for changes in water quality within catchment streams. Due to the potential large input of surface runoff to streams following …

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Formation Of Active Catalytic Sites In Hydrocarbon Synthesis And Reaction, Nattaporn Lohitharn May 2008

Formation Of Active Catalytic Sites In Hydrocarbon Synthesis And Reaction, Nattaporn Lohitharn

All Dissertations

Acid and metal catalysis are considerably important in the chemical industry especially, for the production of transportation fuels. Since a serious concern on the world environment has infringed on the restriction of aromatics contained in gasoline, the demand for clean high-octane branched alkanes for gasoline upgrading has significantly increased. This process involves acid catalyzed n-butane isomerization in which n-butane is converted to isobutane, a primary feedstock for the production of high-octane species. In addition, due to the unpredictable price and the limited resource of petroleum fuel derived crude oil, the attention has shifted to synthetic liquid fuels derived from other …

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Incorporation Of Polydiacetylene Sensors Into Commercial Polymers, Jennifer Kauffman May 2008

Incorporation Of Polydiacetylene Sensors Into Commercial Polymers, Jennifer Kauffman

All Dissertations

Polydiacetylenes (PDAs) exhibit a chromatic response to solvents, temperature, strain and other environmental perturbations. When formed in a solid-state polymerization, the backbone of the polymer is planar and continuous π-overlap is observed. However, when the PDA backbone is distorted by an outside force the extended conjugation is interrupted and an optical shift from blue to red occurs. By exploiting the PDAs properties within polymer systems, smart fibers and films have been created that enhance the original intention of the host. Under this umbrella, a strain sensitive polydiacetylene-polyurethane blend was created using 3 and 4-butoxycarbonylmethylurethane PDA and a medical grade polyurethane, …

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Analysis Of The Impact Of Fuel Price And Bidding Volume On The Engineer's Estimate, Greaton Sellers May 2008

Analysis Of The Impact Of Fuel Price And Bidding Volume On The Engineer's Estimate, Greaton Sellers

All Theses

The research project 'Analysis of the Impact of Fuel Price and Bidding Volume on the Engineer's Estimate' was initiated by the South Carolina Department of Transportation and conducted by Clemson University. This research was executed as a two part study, 'Best Practices for Developing the Engineer's Estimate', which addressed two distinct but related objectives. The first research objective was to fully explore the advantages and disadvantage of alternative methodologies utilized to compile the engineer's cost estimate. This research objective is addressed in Report Volume I. The second research objective, which is addressed in this Report Volume II, was to develop …

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Protocols For Dynamic Spectrum Access, Thomas Royster May 2008

Protocols For Dynamic Spectrum Access, Thomas Royster

All Dissertations

Protocols for modulation selection, initial transmitter power adjustment, modulation and coding adaptation, and transmitter power adaptation are presented. Most adaptive protocols in the literature are for full-duplex communication and they require channel estimation (e.g., using training symbols); however, our protocols are for half-duplex packet radios and they do not require estimation of the channel for adaptation. Instead, our protocols are driven by statistics that can be derived from the receiver's demodulator or decoder. We present the protocols in the context of their application to dynamic spectrum access networks. Our protocols are designed for adaptive radios, of which software-defined radios and …

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Anaerobic Biodegradation Of Ethylene Dibromide And 1,2-Dichloroethane In The Presence Of Fuel Hydrocarbons, James Henderson May 2008

Anaerobic Biodegradation Of Ethylene Dibromide And 1,2-Dichloroethane In The Presence Of Fuel Hydrocarbons, James Henderson

All Dissertations

Field evidence from underground storage tank (UST) sites where leaded gasoline leaked indicates the lead scavengers 1,2-dibromoethane (ethylene dibromide, or EDB) and 1,2-dichloroethane (1,2-DCA) may be present in groundwater at levels that pose unacceptable risk. These compounds are seldom tested for at UST sites. Although dehalogenation of EDB and 1,2-DCA is known to occur, the effect of fuel hydrocarbons on their biodegradability under anaerobic conditions is poorly understood. Microcosms (2 L glass bottles) were prepared with soil and groundwater from a UST site in Clemson, South Carolina, using samples collected from the source (containing residual fuel) and less contaminated downgradient …

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Real-Time Raman Spectroscopy And Wide-Angle X-Ray Diffraction During Single-Layer And Multi-Layer Blown Film Extrusion, Giriprasath Gururajan May 2008

Real-Time Raman Spectroscopy And Wide-Angle X-Ray Diffraction During Single-Layer And Multi-Layer Blown Film Extrusion, Giriprasath Gururajan

All Dissertations

Properties exhibited by blown films are controlled by the microstructure developed during their processing. Therefore, real-time measurement of microstructure during the blown film extrusion can help in better control and optimization of the process needed to obtain desired properties. The objectives of this research were (i) to conduct real-time microstructural measurements during single-layer and multi-layer blown film extrusion of polypropylene (PP) and low-density polyethylene (LDPE) using real-time Raman spectroscopy; (ii) to conduct real-time wide-angle X-ray diffraction (WAXD) during single-layer blown film extrusion of LDPE to obtain crystallinity and orientation values during the process; and (iii) to investigate the effect of …

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Investigating The Role Of Prototyping In Mechanical Design Using Case Study Validation, David Stowe May 2008

Investigating The Role Of Prototyping In Mechanical Design Using Case Study Validation, David Stowe

All Theses

The purpose of this research is to explore the application of prototyping in the design process through a case study analysis using structured interviews, an ethnographic study, and documents analysis, to determine what factors and practices result in successful prototyping. In doing so, research questions are established, a prototyping process is developed to assist the investigation, and classification systems are created to organize data collected in the study. As part of the case study, an interview is formulated to answer the proposed research questions and a literature survey of prototyping in design is used to create a larger analytical foundation. …

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Synthesis And Dielectric Properties Of Nanocrystalline Barium Titanate And Silver/Barium Titanate Particles, Hiroki Maie May 2008

Synthesis And Dielectric Properties Of Nanocrystalline Barium Titanate And Silver/Barium Titanate Particles, Hiroki Maie

All Theses

The increasing needs for further functionality, higher performance, and miniaturization of electronic devices have highly demanded down-size and volume-efficiency of electronic components such as multilayer ceramic capacitors (MLCCs). To meet this demand, the use of high dielectric constant material with nanometer size and spherical shape is considered as requirements. Embedded capacitors are an important emerging technology for meeting the performance and functionality requirements of next-generation electronic devices. One major obstacle for implementing this technology is the scarcity of dielectric materials with appropriate dielectric and mechanical properties was mainly discussed

Considering these backgrounds, this research is devoted to synthesis of high …

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Factors Affecting The Performance Of Brick Veneer Construction, Jocelyn Dickie May 2008

Factors Affecting The Performance Of Brick Veneer Construction, Jocelyn Dickie

All Theses

The first topic focused on in this report is the height restriction imposed by the masonry standard for brick veneer on wood frame backing. The current US standard (ACI 530-05/ASCE 5-05/TMS 402-05 Building Code Requirements for Masonry Structures) does not allow brick veneer to extend more than thirty feet above the foundation when supported by wood framing. These prescriptive requirements are compared with those of the Canadian (CSA 304.1-04) and Australian (AS 3700-2001) masonry standards. The logic found for this height restriction is based on the vertical differential movement caused by moisture and thermal expansion of the brick veneer and …

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Improved Closed-Form Bounds On The Performance Of Convolutional Codes With Correlated Rayleigh Fading, Dwight Hutchenson May 2008

Improved Closed-Form Bounds On The Performance Of Convolutional Codes With Correlated Rayleigh Fading, Dwight Hutchenson

All Theses

New bounds on the probability of bit error are presented for a coded communication system with binary antipodal modulation and soft-decision maximum-likelihood decoding over a correlated Rayleigh-fading channel. The bounds are closed-form expressions in terms of the code's transfer function; they are illustrated by considering a system using convolutional encoding. A long-standing conjecture regarding the worst-case error event in correlated Rician fading is proven for the special case of correlated Rayleigh fading, and it is used in the development of some of the new bounds. The bounds are shown to be tighter than previously developed closed-form bounds for communications using …

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Surface Functionalized Colloidal Particles And Polymer Synthesis For Led Based Applications, Zachary Hunt May 2008

Surface Functionalized Colloidal Particles And Polymer Synthesis For Led Based Applications, Zachary Hunt

All Theses

Over the last decade atom transfer radical polymerization, ATRP, has become a commonplace route by which tailored polymers can be synthesized. The advent of this polymerization mechanism has enabled the controlled synthesis of block and multi-block polymer systems that maintain a terminal bromine functionality that adds further versatility to the synthesized polymers.
Additionally, in the last few years 'click' chemistry has come to light as an efficient method of selectively linking molecules under mild conditions (e.g. room temperature and aqueous systems). In particular, the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has become more and more popular, and provides another route by …

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The Awe Wall: A Novel Robotic Surface, Martha Kwoka May 2008

The Awe Wall: A Novel Robotic Surface, Martha Kwoka

All Theses

In this thesis, we present fundamental contributions towards AWE, a novel 'Animated Work Environment', which seeks to introduce robotics at the architectural scale to modify environments in real time to the changing needs and moods of their occupants. Part of AWE is a robotic surface, or wall, featuring a multiple folding panel structure. The panels of the AWE wall feature embedded IT and adapt to the current movements and tasks of the user. We describe the overall AWE concept and discuss the construction of the robot surface, its motion planning and its control, and all experiments run to this point.

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On New Applications And Sensitivity Enhancement Of Cantilever-Based Sensing Systems, Calvin Bradley May 2008

On New Applications And Sensitivity Enhancement Of Cantilever-Based Sensing Systems, Calvin Bradley

All Theses

Cantilever-based Sensing Systems (CSS) have become a focal area for research with the rise of micro- and nanotechnology. History has led us to use cantilever beams as one of the foremost sensing devices for small scale applications, beginning with the atomic force microscopy, and then being expanded into numerous sensor devices. The CSS include such applications as accelerometers, thermal and chemical sensors which are expanding into the applications of mass sensing and material characterization. Soon, this technology may be used in 'lab on chip' biosensing applications.
This study covers the experimentation into new CSS applications and sensitivity enhancement. In order …

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The Formation Of Halonitromethanes In Wastewater Treatment Plant Effluents, Jesse Addison May 2008

The Formation Of Halonitromethanes In Wastewater Treatment Plant Effluents, Jesse Addison

All Theses

Disinfection by-products (DBPs) have been a water treatment concern since their discovery in the 1970's. Today, only eleven drinking water DBPs are regulated by the Environmental Protection Agency (EPA). However, over 500 DBPs have been identified in drinking waters with advances in analytical methods within the last two decades. Halonitromethanes (HNMs) were among the fifty-plus unregulated high-priority DBPs that were monitored for and detected in drinking waters in a recent nationwide occurrence study funded by EPA. The toxicology studies conducted in recent years showed that HNMs are one of the most cytotoxic and genotoxic classes among the emerging DBPs, and …

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A Systems Approach To The Design Of A Two Dimensional Cell Printer, Albert Hill May 2008

A Systems Approach To The Design Of A Two Dimensional Cell Printer, Albert Hill

All Theses

Tissue engineering research has the potential to improve the current opportunities for replacement organs and tissues. Precise placement of cells has proven difficult in the early stages of this research. Bioprinting is an important research area that has the potential to accurately position cells and biological materials for tissue engineering. This paper describes the attempt to obtain micrometer accuracy in the placement of cells using a systems approach and technology derived from the Hewlett Packard 500 series of printers and their cartridges the HP26 series. The paper discusses the research and design of a custom printing system that allows control …

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Modeling Of The Effect Of Tool Wear On Cutting Forces In Turning, Yu Long May 2008

Modeling Of The Effect Of Tool Wear On Cutting Forces In Turning, Yu Long

All Dissertations

Machining is the most widely used and efficient material removal process, and tool wear in machining is usually of great interest in order to improve machining efficiency and effectiveness. Cutting tool wear patterns such as the flank and crater wear and the dead metal zone (DMZ) may induce the cutting tool geometry variation in machining. As a result, cutting forces may increase or decrease due to the change of tool effective cutting geometry during machining operations. A quantitative understanding of and the ability to predict cutting forces in relation to tool wear are important to the tool life estimation, chatter …

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Physics-Based Shape Morphing And Packing For Layout Design, Hong Dong May 2008

Physics-Based Shape Morphing And Packing For Layout Design, Hong Dong

All Dissertations

The packing problem, also named layout design, has found wide applications in the mechanical engineering field. In most cases, the shapes of the objects do not change during the packing process. However, in some applications such as vehicle layout design, shape morphing may be required for some specific components (such as water and fuel reservoirs). The challenge is to fit a component of sufficient size in the available space in a crowded environment (such as the vehicle under-hood) while optimizing the overall performance objectives of the vehicle and improving design efficiency. This work is focused on incorporating component shape design …

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