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Articles 331 - 360 of 366

Full-Text Articles in Mechanical Engineering

Analytical Solutions Using High Order Composite Laminate Theory For Honeycomb Sandwich Plates With Viscoelastic Frequency Dependent Damping, Nan Shan Aug 2011

Analytical Solutions Using High Order Composite Laminate Theory For Honeycomb Sandwich Plates With Viscoelastic Frequency Dependent Damping, Nan Shan

All Theses

Analytical methods allow parametric changes in geometric and material properties of a honeycomb sandwich plate for studies of stiffness, mass, and damping characteristics with low computational cost. However, studies based on analytical methods are still limited with frequency independent damping models. Specifically, previous analytical models have not consider the frequency dependent damping for viscoelastic honeycomb core sandwich composites, while some work has been done on studying the honeycomb sandwich plate using finite element method, which can be computationally expensive for multiple parameter studies. Therefore, in this work, the honeycomb sandwich plate is studied analytically based on the cellular material theory, …

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Extracting Depth Information From Stereo Vision System, Using A Correlation And A Feature Based Methods, Mahmoud Abdelhamid Aug 2011

Extracting Depth Information From Stereo Vision System, Using A Correlation And A Feature Based Methods, Mahmoud Abdelhamid

All Theses

This thesis presents a new method to extract depth information from stereo-vision acquisitions using a feature and a correlation based approaches. The main implementation of the proposed method is in the area of Autonomous Pick & Place, using a robotic manipulator. Current vision-guided robotics are still based on a priori training and teaching steps, and still suffer from long response time.
The study uses a stereo triangulation setup where two Charged Coupled Devices CCDs are arranged to acquire the scene from two different perspectives. The study discusses the details of two methods to calculate the depth; firstly a correlation matching …

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Viscoelastic Damping Of Hexagonal Honeycomb Sandwich Panels, Nikhil Seera Aug 2011

Viscoelastic Damping Of Hexagonal Honeycomb Sandwich Panels, Nikhil Seera

All Theses

Composite sandwich structures with a viscoelastic core material constrained between thin stiff face sheets are an effective means of damping in engineering applications. Damping introduces energy dissipation which helps control vibration amplitudes. Conventional Hexagonal honeycombs are often referred to as regular honeycombs and are defined by cellular geometry with effective positive Poisson's ratio. Regular honeycombs are commonly used for the cores of sandwich plates because of their low density and high stiffness properties. Honeycombs with negative in-plane Poisson's ratio are known as Auxetic honeycombs and offer enhancement of mechanical properties such as impact absorption, damage resistance, when compared to regular …

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Electrokinetic Transport And Manipulation Of Particles In Curved Microchannels, Junjie Zhu Aug 2011

Electrokinetic Transport And Manipulation Of Particles In Curved Microchannels, Junjie Zhu

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The investigation of electrokinetic particle transport in confined microchannels has practical significances in a variety of applications ranging from traditional gel electrophoresis to electrokinetic microfluidics-based lab-on-a-chip devices. To date, however, studies on particle electrokinetics have been limited to primarily theoretical or numerical analyses in straight microchannels of simple geometries. Very little work has been done on electrokinetic particle motions in real microchannels which usually consist of one or multiple turns. This thesis is dedicated to the fundamental and applied studies of electrokinetic transport and manipulation of particles in various curved microchannels using a combined experimental, theoretical, and numerical method.
First, …

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Multi-Length Scale Modeling Of The High-Pressure, Large-Strain, High-Strain-Rate Response Of Soda-Lime Glass, William Bell Aug 2011

Multi-Length Scale Modeling Of The High-Pressure, Large-Strain, High-Strain-Rate Response Of Soda-Lime Glass, William Bell

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Development of new transparent armor systems is essential for the protection of the current and future US armed forces, especially in light of the recent military operations The Operation Iraqi Freedom in Iraq and The Operation Enduring Freedom in Afghanistan. These conflicts have introduced a new military theater without a well-defined battle front and new types of threats (e.g. improvised explosive devices, IEDs). Development and modeling of new transparent armor systems for use in numerous applications from vehicle windows to face shields is a current area of thrust aimed at addressing the shortcomings of existing systems in order to better …

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An Investigation Of The Effects Of Surfactant Monolayers On Natural Convection Heat Transfer And Evaporative Mass Transfer, Steven Bower Aug 2011

An Investigation Of The Effects Of Surfactant Monolayers On Natural Convection Heat Transfer And Evaporative Mass Transfer, Steven Bower

All Dissertations

Laboratory experiments are presented that reveal the effects of surfactant monolayers on natural convection heat transfer and evaporation from bodies of water; more specifically, the situation is studied where the bulk temperature of the water is greater than the temperature of the air so that evaporative convection occurs. Four sets of experiments were performed in a laboratory environment on insulated tanks of different widths and depths for the following surface conditions: 1) clean surface, 2) oleyl alcohol covered surface, 3) stearic acid covered surface, and 4) stearyl alcohol covered surface. An infrared (IR) camera was used to verify the existence …

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Computational-Analysis Assisted Introduction Of Friction Stir Welding Into Development Of Light-Weight High-Survivability Military Vehicles, Guruprasad Arakere Aug 2011

Computational-Analysis Assisted Introduction Of Friction Stir Welding Into Development Of Light-Weight High-Survivability Military Vehicles, Guruprasad Arakere

All Dissertations

High strength aluminum alloys with superior blast/ballistic resistance against armor piercing (AP) threats and with high vehicle light-weighing potential are being increasingly used as military-vehicle armor. Due to the complex structure of these vehicles, they are commonly constructed through joining (mainly welding) of the individual components. Unfortunately, these alloys are not very amenable to conventional fusion based welding technologies (e.g. Gas Metal Arc Welding (GMAW)) and in-order to obtain high-quality welds, solid-state joining technologies such as Friction Stir Welding (FSW) have to be employed. However, since FSW is a relatively new and fairly complex joining technology, its introduction into advanced …

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Development Of A Second-Stage Novice Driver Education And Training Program, John Wagner, M Jensen, F Switzer, K Alexander, P Pidgeon Jul 2011

Development Of A Second-Stage Novice Driver Education And Training Program, John Wagner, M Jensen, F Switzer, K Alexander, P Pidgeon

Publications

Novice drivers are overrepresented in traffic crashes and fatalities. Traffic crashes are the leading cause of death for 16 to 20 year olds and account for one in three deaths in this age group (NHTSA, 2008; CDC, 2010). Significant research has been conducted developing and analyzing driver education and training and education programs. Effective programs identify their target audiences and tailor the program paradigm and methods to their developmental needs. This paper develops a second-stage safe driver program for novice drivers focusing on classroom and behind-the-wheel instruction for four common driving skills and situations: braking, avoiding obstacles, losing control, and …

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Modeling And Finite Element Analysis Methods For The Dynamic Crushing Of Honeycomb Cellular Meso-Structures, Jesse Schultz May 2011

Modeling And Finite Element Analysis Methods For The Dynamic Crushing Of Honeycomb Cellular Meso-Structures, Jesse Schultz

All Theses

The effective static mechanical properties, such as the moduli of elasticity and rigidity and Poisson's ratio, of honeycomb cellular meso-structures are capable of control due to variations of their cellular geometry. While the dynamic properties of these structures are a popular topic of research, there is a lack of both consistent modeling methods and generalizations in terms of honeycomb cellular geometry. In order to fill these gaps, this study presents a standard set of methods for the finite element analysis (FEA) of honeycomb cellular materials subject to dynamic loading conditions, as well as illustrates the effects of the cellular geometry …

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Joule Heating Effects On Electrokinetic Transport In Constriction Microchannels, Sriram Sridharan May 2011

Joule Heating Effects On Electrokinetic Transport In Constriction Microchannels, Sriram Sridharan

All Theses

Microfluidic technology involving multidisciplinary studies including MEMS, chemistry, physics, fluids and heat transfer has been developed into a promising research field in the recent decade. If offers many advantages over conventional laboratory techniques like reduced reagent consumption, faster analysis, easy fabrication and low chemical waste. Microfluidic lab-on-a-chip devices have been used to manipulate cells and particles like sorting, separating, trapping, mixing and lysing. Microfluidic manipulation can be achieved through many methods and insulator based dielectrophoresis (iDEP) is one of the highly used method in the recent years. In iDEP, both DC and AC voltages can be applied to the remote …

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Connective Complexity Methods For Analysis And Prediction In Engineering Design, James Mathieson May 2011

Connective Complexity Methods For Analysis And Prediction In Engineering Design, James Mathieson

All Theses

Complexity is an aspect of engineering design that is often addressed directly with the principle that 'designs should be simple'. However, such a principle fails to offer an effective means of quantifying the complexity of a given design for comparison and decision making. The measurement of complexity within a specific representations and domains has been well established. However, such measurements are inherently limited in their applicability and not always clear in their implications. This research presents a method of measuring complexity from different engineering representations in a consistent manner and explores the application of these measures.
The development of a …

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Fluid Dynamics Of Cell Printing, Ping He May 2011

Fluid Dynamics Of Cell Printing, Ping He

All Dissertations

Cell printing is an emerging technology that uses droplets to deliver cells to desired positions with resolution potentially comparable to the size of single cells. In particular, ink–jet based cell printing technique has been successfully used to build simple bio–constructs and has shown a promise in building complex bio–structures or even organs. Two important issues in ink–jet based cell printing are the moderate survival rate of delicate cells and the limited cell placement resolution. Resolving these issues is critical for the ink–jet based cell printing techniques to realize their full potential.
In this work, we use numerical simulations to reconstruct …

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Finite Element Analysis Prediction Of Stresses In H.L. Hunley Submarine By Global-To-Local Model Coordination, Aditya Sai Nag Choragudi May 2011

Finite Element Analysis Prediction Of Stresses In H.L. Hunley Submarine By Global-To-Local Model Coordination, Aditya Sai Nag Choragudi

All Theses

H.L Hunley was a submarine of the Confederate States of America that participated in the American Civil War. On February 17, 1864, H.L.Hunley created history by becoming the first submarine to sink a enemy ship after its attack on USS Houstanic. After Hunley never returned to the shore and the details of its wreck were unknown. On August 8, 2000, H. L Hunley was brought to the surface after 136 years of its wreckage. The submarine is currently at the Warren Lasch Conservation Center located in Charleston.
This study focuses on the structural analysis of the H.L Hunley submarine to …

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Multi-Scale Modeling Of The Fontan Circulation Using A Mock Circulatory System, John Chiulli May 2011

Multi-Scale Modeling Of The Fontan Circulation Using A Mock Circulatory System, John Chiulli

All Theses

The Fontan circulation is the result of a series of operations performed to save the lives of children born with univentricular circulations. The Fontan procedure achieves venous return to the pulmonary circulation without a ventricular power source. The load on the heart is reduced to normal, and these patients can lead a normal life into adulthood, although late complications continue to prevent normal lifespan. A unique feature of the Fontan circulation is the dependency of inferior vena cava flow on respiration. The Fontan circulation has been modeled experimentally using an adjustable mock circulatory system, which for the first time includes …

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Parametric Amplification In The Context Of Vibratory Energy Harvesting, Roger Bode May 2011

Parametric Amplification In The Context Of Vibratory Energy Harvesting, Roger Bode

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Using a vibratory energy harvester (VEH) to independently power a sensor has become an increasingly popular topic due to the small amount of power current sensors require to operate. This can be achieved by scavenging energy from the ambient environment where the sensor is located. Numerous linear and nonlinear energy harvesters have been proposed in order to deal with various vibratory environments, along with improving the power production and/or bandwidth of the device.
In this thesis, we propose a technique to harvest energy from excitation sources that possess two frequency components: a fundamental component with large energy content, and a …

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Requirements Determination Of A Novel Non-Pneumatic Wheel Shear Beam For Low Rolling Resistance, Niranjan Thyagaraja May 2011

Requirements Determination Of A Novel Non-Pneumatic Wheel Shear Beam For Low Rolling Resistance, Niranjan Thyagaraja

All Theses

The hysteretic loss associated with cyclic shear in the elastomeric shear layer is one of the prevailing concerns for the development of a low rolling loss non-pneumatic wheel. We propose to eliminate the hysteretic losses associated with the elastomeric shear layer and thus, reduce the corresponding rolling resistance by using linear elastic materials which are inherently non-hysteretic. Since the shear modulus of a viscoelastic shear layer is less than that of an elastic material by several orders of magnitude, the challenge to achieve a low effective shear modulus shear layer with linear elastic materials directs towards the development of a …

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Agent-Based Under Hood Packing, Karthik Ravindranath May 2011

Agent-Based Under Hood Packing, Karthik Ravindranath

All Theses

Improving vehicle performance and passenger comfort has been a prime engineering concern and focus of research for many years in automotive design. Turning to high-performance components in an effort to improve vehicle performance alone is often not enough and their placement and interactions with other components should also be an integral part of the improvement process. With the advancement in hybrid electric vehicle technology, the packing of components under the hood is ever more essential and challenging. Under hood packing is a multi-objective optimization problem with many, and mostly conflicting objectives. A non-deterministic multi-objective evolutionary algorithm needs to be integrated …

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Evaluation Of Biomass And Coal Briquettes For A Spreader Stoker Boiler Using An Experimental Furnace - Modeling And Test, Gavin Wiggins May 2011

Evaluation Of Biomass And Coal Briquettes For A Spreader Stoker Boiler Using An Experimental Furnace - Modeling And Test, Gavin Wiggins

All Theses

The compliance of coal-fired boilers with emissions regulations is a concern for many facilities. The introduction of biomass briquettes in industrial boilers can help to reduce greenhouse gas emissions and coal usage. In this research project, a thermodynamic chemical equilibrium model was derived and analytical simulations performed for a coal boiler system for several types of biomass fuels such as beech, hickory, maple, poplar, white oak, willow, sawdust, torrefied willow, and switchgrass. The biomass emissions were compared to coal and charcoal emissions. The chemical equilibrium analysis numerically estimated the emissions of CO, CO2, NO, NO2, N2O, SO2, and SO3. When …

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Implementation Of Delayed-Feedback Controllers On Continuous Systems And Analysis Of Their Response Under Primary Resonance Excitations, Yousef Qaroush May 2011

Implementation Of Delayed-Feedback Controllers On Continuous Systems And Analysis Of Their Response Under Primary Resonance Excitations, Yousef Qaroush

All Dissertations

During the last three decades, a considerable amount of research has been directed toward understanding the influence of time delays on the stability and stabilization
of dynamical systems. From a control perspective, these delays can either have a compounding and destabilizing effect, or can actually improve controllers'
performance. In the latter case, additional time delay is carefully and deliberately introduced into the feedback loop so as to augment inherent system delays and
produce larger damping for smaller control efforts. While delayed-feedback algorithms have been successfully implemented on discrete dynamical systems with
limited degrees of freedom, a critical issue appears in …

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A Methodology For The Analysis Of In-Vehicle Operating Data And Design Of Intelligent Vehicle Systems For Improved Automotive Safety, Matthew Jensen May 2011

A Methodology For The Analysis Of In-Vehicle Operating Data And Design Of Intelligent Vehicle Systems For Improved Automotive Safety, Matthew Jensen

All Dissertations

Every year global motorization increases as more motor vehicles are manufactured, and the total number of vehicle miles traveled rises. These increased travel opportunities result in higher numbers of injuries, fatalities, and monetary losses associated with traffic-related crashes. In the last decade, hundreds of thousands of people were killed by vehicle collisions in the United States. The World Health Organization has labeled traffic crashes as the ninth leading cause of global disease; by the year 2020, traffic crashes are expected to rise to number three. An opportunity exists to improve global human safety through research and innovation in driver training …

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High Resolution Vision-Based Servomechanism Using A Dynamic Target With Application To Cnc Machines, Carlos Montes-Solano May 2011

High Resolution Vision-Based Servomechanism Using A Dynamic Target With Application To Cnc Machines, Carlos Montes-Solano

All Dissertations

This dissertation introduces a novel three dimensional vision-based servomechanism with application to real time position control for manufacturing equipment, such as Computer Numerical Control (CNC) machine tools. The proposed system directly observes the multi-dimensional position of a point on the moving tool relative to a fixed ground, thus bypassing the inaccurate kinematic model normally used to convert axis sensor-readings into an estimate of the tool position.

A charge-coupled device (CCD camera) is used as the position transducer, which directly measures the current position error of the tool referenced to an absolute coordinate system. Due to the direct-sensing nature of the …

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Mapping Problem And Requirements To Solution: Document Analysis Of Senior Design Projects, Shraddha Joshi Dec 2010

Mapping Problem And Requirements To Solution: Document Analysis Of Senior Design Projects, Shraddha Joshi

All Theses

Formulating and solving engineering problems and designing solutions that meet the established requirements are important skills that graduating engineering students need to possess. However, there are noticeable gaps in the literature with respect to understanding how the formulation of design problems and establishment of requirements affect the final design solution. This thesis is an initial attempt to understand the influence of level of detail of problem statement and requirements on the level of detail of final solution. In doing so, a document analysis of final reports from senior design class collected over a period of ten years from 1999 to …

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Pulse Echo Ultrasonic Testing Of Adhesive Bonded Joints For Automotive Applications, Arun Ganapathi Dec 2010

Pulse Echo Ultrasonic Testing Of Adhesive Bonded Joints For Automotive Applications, Arun Ganapathi

All Theses

The growing prominence of adhesive bonding technology in automotive manufacture has necessitated the development of reliable and robust quality assurance techniques. Of the different Nondestructive testing technologies available, Ultrasonic testing has shown itself to be the most promising technique to satisfy the requirements in automobile production. The current work attempts to apply two variations of the Ultrasonic Pulse Echo technique namely Contact and Immersion testing for inspecting typical hem bonded automotive joints. The joints have been tested for disbond at the various metal-adhesive interfaces by using an ultrasonic scan comparison method which compares the acquired signals against a reference scan …

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A Computational Method For Analysis Of Material Properties Of A Non-Pneumatic Tire And Their Effects On Static Load Deflection, Vibration And Energy Loss From Impact Rolling Over Obstacles, Akshay Narasimhan Dec 2010

A Computational Method For Analysis Of Material Properties Of A Non-Pneumatic Tire And Their Effects On Static Load Deflection, Vibration And Energy Loss From Impact Rolling Over Obstacles, Akshay Narasimhan

All Theses

One of the potential sources of vibration during rolling of a non pneumatic tire is the buckling phenomenon and snapping back of the spokes in tension when they enter and exit the contact zone. Another source of noise was hypothesized due to a flower pedal ring vibration effect due to discrete spoke interaction with the ring and contact with the ground during rolling as the spokes cycle between tension and compression. Transmission of vibration between the ground force, ring and spokes to the hub was also considered to be a significant contributor to vibration and noise characteristics of the Tweel. …

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A Computational Investigation Of Contact Pressure For A Non-Pnemautic Wheel With A Meta-Material Shear Band, Renuka Jagadish Dec 2010

A Computational Investigation Of Contact Pressure For A Non-Pnemautic Wheel With A Meta-Material Shear Band, Renuka Jagadish

All Theses

One of the missions of National Aeronautics Space Administration (NASA) is to develop a vehicle that can travel for a longer distance on the moon and have a greater degree of mobility compared to the currently used Lunar Roving Vehicles (LRV). This led to the development of the All-Terrain Hex-Limed Extra-Terrestrial Explorer (ATHLETE), which requires a significant advance in the type of wheels that must be used on this highly mobile lander. The Michelin Lunar Wheel, which is a non-pneumatic tire invented by Michelin Researche et Technologie has been identified as one of the key designs capable of performing on …

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Advanced Automotive Thermal Management - Operation Of An Electric Radiator Fan Array For Reduced Electric Power Consumption, Amit Jagarwal Dec 2010

Advanced Automotive Thermal Management - Operation Of An Electric Radiator Fan Array For Reduced Electric Power Consumption, Amit Jagarwal

All Theses

The depletion of fossil fuel reserves and the limited renewable energy resources have raised public awareness about the need to improve fuel efficiency in ground transportation vehicles. The internal combustion engine remains one of the primary industrial machines using gasoline or diesel fuel to produce mechanical work. In these engines, the cooling system performs the vital role of removing waste heat to ensure normal combustion processes in the cylinders. To accomplish this task, the radiator, the radiator fan(s), the thermostat valve, and the water pump operated by circulating cooling fluid through the engine block and rejecting heat to the atmosphere. …

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Incorporating Function Structures Into Morphological Charts: A User Study, Jenkins Richardson Iii Dec 2010

Incorporating Function Structures Into Morphological Charts: A User Study, Jenkins Richardson Iii

All Theses

A morphological chart is an ideation tool that represents a large qualitative design space. Currently, morphological charts use a function list to as the function representation of the design problem. Using the morphological chart means (solutions) that can perform each function are generated. Combining one means from each function produces an integrated conceptual design solution. By repeating this process with all possible combination contained in the morphological chart, a long list of conceptual design solutions will be generated, although not all will be practical. This long list of potential design solutions is difficult to analyze and there are limited systematic …

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Mass And Assembly Time Reduction For Future Generation Automotive Vehicles Based On Existing Vehicle Model, Essam Namouz Dec 2010

Mass And Assembly Time Reduction For Future Generation Automotive Vehicles Based On Existing Vehicle Model, Essam Namouz

All Theses

This research presents method for evaluating the lightweightedness of a vehicle and an approach for vehicle assembly time savings potential developed through a case study. The Lazy Part Identification method for mass reduction specifically addresses those components whose primary purpose is to aid in manufacturing and assembly rather than to provide end-user function. Seven specific laziness indicators are described and illustrated: rigid-to-rigid connection, support for a flexible, non-moving part, positioning feature, duplicate geometry, fastener, bridging system, and material flow restriction. These indicators are used to evaluate individual vehicle components as part of a proposed method for identifying mass reduction potential. …

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Analysis Of Alternative Manufacturing Processes For Lightweight Biw Designs, Using Analytical Hierarchy Process, Srinath Vijayakumar Dec 2010

Analysis Of Alternative Manufacturing Processes For Lightweight Biw Designs, Using Analytical Hierarchy Process, Srinath Vijayakumar

All Theses

The main objective of the analysis was to investigate the forming of Body in White (BIW) panels using alternative processes most suitable for replacing the conventional press working process in order to achieve a reduction in the total mass of the vehicle body structure. The selection of the alternatives was guided by multi criteria decision making tool, the Analytic Hierarchy Process (AHP). Here the alternatives were selected based on their relative importance to the different manufacturing attributes considered. The selected processes were applied to the manufacturing of different parts of BIW indicated in the BOM along with suggestion of the …

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Pulsed-Laser Direct Writing Of Biological Materials, Yafu Lin Dec 2010

Pulsed-Laser Direct Writing Of Biological Materials, Yafu Lin

All Dissertations

Laser direct writing, developed based on modified laser-induced forward transfer (LIFT), has been emerging as one of the most promising biofabrication techniques. While some studies have been conducted to investigate laser direct writing of biological materials, there are some key challenges such as mechanisms of bubble formation, droplet formation and process-induced cell injury that have not been well elucidated. The objective of this dissertation is to study laser-induced droplet formation dynamics and process-induced cell injury in pulsed-laser direct writing of biological materials, and improve the existing laser direct-write techniques.
Phase explosion is identified as the dominant bubble formation mechanism in …

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