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2009

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Articles 1 - 30 of 654

Full-Text Articles in Mechanical Engineering

Ultra-Thin Super High Frequency Two-Port Aln Contour-Mode Resonators And Filters, Matteo Rinaldi, Chiara Zuniga, Chengjie Zuo, Gianluca Piazza Feb 2013

Ultra-Thin Super High Frequency Two-Port Aln Contour-Mode Resonators And Filters, Matteo Rinaldi, Chiara Zuniga, Chengjie Zuo, Gianluca Piazza

Matteo Rinaldi

This paper reports on the demonstration of a new class of ultra-thin (250 nm thick) Super High Frequency (SHF) AlN piezoelectric two-port resonators and filters. A thickness field excitation scheme was employed to excite a higher order contour extensional mode of vibration in an AlN nano plate (250 nm thick) above 3 GHz and synthesize a 1.96 GHz narrow-bandwidth channel-select filter. The devices of this work are able to operate over a frequency range from 1.9 to 3.5 GHz and are employed to synthesize the highest frequency MEMS filter based on electrically self-coupled AlN contour-mode resonators. Very ...


Method Of Transferring Strained Semiconductor Structure, Michael Nastasi Dec 2009

Method Of Transferring Strained Semiconductor Structure, Michael Nastasi

Mechanical & Materials Engineering Faculty Publications

The transfer of strained semiconductor layers from one substrate to another substrate involves depositing a multilayer structure on a substrate having surface contaminants. An interface that includes the contaminants if formed in between the deposited layer and the substrate. Hydrogen atoms are introduced into the structure and allowed to diffuse to the interface. Afterward, the deposited multilayer structure is bonded to a second substrate and is separated away at the interface, which results in transferring a multilayer structure from one substrate at least one strained semiconductor layer and at least one strain-induced seed layer. The strain-induced seed layer can be ...


Experimental Study On Viscosity And Phase Segregation Of Al–Si Powders In Microsemisolid Powder Forming, Yufeng Wu, Iver E. Anderson, Thomas A. Lograsso, Gap-Yong Kim Dec 2009

Experimental Study On Viscosity And Phase Segregation Of Al–Si Powders In Microsemisolid Powder Forming, Yufeng Wu, Iver E. Anderson, Thomas A. Lograsso, Gap-Yong Kim

Mechanical Engineering Publications

Semisolid powder forming is a promising approach for near-net shape forming of features in macro-/microscale. In this paper, viscosity and phase segregation behavior of Al–Si powders in the semisolid state were studied with back extrusion experiments. The effects of process parameters including shear rate, extrusion ratio, heating time, and precompaction pressure were analyzed using the design of experiments method. The results showed that the effects of shear rate, extrusion, ratio and heating time were statistically significant factors influencing the viscosity. The semisolid state powders showed a shear thinning behavior. Moreover, microstructure analysis of extruded parts indicated severe phase ...


Configuration Recognition, Communication Fault Tolerance And Self-Reassembly For The Ckbot, Michael G. Park Dec 2009

Configuration Recognition, Communication Fault Tolerance And Self-Reassembly For The Ckbot, Michael G. Park

Publicly Accessible Penn Dissertations

We present and experimentally verify novel methods for increasing the generality of control, autonomy and reliability for modular robotic systems. In particular, we demonstrate configuration recognition, distributed communication fault tolerance, and the organization and control of self-reassembly with the Connector Kinetic roBot (CKBot). The primary contribution of this work is the presentation and experimental verification of these innovative methods that are general and applicable to other modular robotic systems. We describe our CKBot system and compare it to other similar, state-of-the-art modular robotic systems. Our description and comparison highlights various design developments, features, and notable achievements of these systems. We ...


Degeneration Affects The Structural And Tissue Mechanics Of The Intervertebral Disc, Grace D. O'Connell Dec 2009

Degeneration Affects The Structural And Tissue Mechanics Of The Intervertebral Disc, Grace D. O'Connell

Publicly Accessible Penn Dissertations

The intervertebral disc is comprised of mechanically and structurally unique substructures including the annulus fibrosus and the nucleus pulposus, which function together to support and absorb the large complex spinal loads. Disc degeneration causes drastic changes in the composition and may lead to altered mechanics; however, the changes in the internal mechanical function of the nucleus and annulus are not well understood. Moreover, herniation of nucleus pulposus material through the posterior annulus causes low back pain and may alter the mechanical function of the disc. Discectomy, a procedure to relieve the pain by removing the herniated material; however, the effect ...


Efficient Rotation Algorithms For Texture Evolution, Mark W. Esty Dec 2009

Efficient Rotation Algorithms For Texture Evolution, Mark W. Esty

Theses and Dissertations

Texture evolution is a vital component of many computational tools that link structure, properties and processes of polycrystalline materials. By definition, this evolution process involves the manipulation, via rotation, of points in orientation space. The computational requirements of the current methods being used to rotate crystalline orientations are a significant limiting factor in the drive to merge the texture information of materials into the engineering design process. The goal of this research is to find and implement a practical rotation algorithm that can significantly decrease the computation time required to rotate macroscopic and microscopic crystallographic textures. Three possible algorithms are ...


Haptic Displayof Realistic Tool Contact Via Dynamically Compensated Control Of A Dedicated Actuator, William Mcmahan, Katherine J. Kuchenbecker Dec 2009

Haptic Displayof Realistic Tool Contact Via Dynamically Compensated Control Of A Dedicated Actuator, William Mcmahan, Katherine J. Kuchenbecker

Departmental Papers (MEAM)

High frequency contact accelerations convey important information that the vast majority of haptic interfaces cannot render. Building on prior work, we present an approach to haptic interface design that uses a dedicated linear voice coil actuator and a dynamic system model to allow the user to feel these signals. This approach was tested through use in a bilateral teleoperation experiment where a user explored three textured surfaces under three different acceleration control architectures: none, constant gain, and dynamic compensation. The controllers that use the dedicated actuator vastly outperform traditional position-position control at conveying realistic contact accelerations. Analysis of root mean ...


Self-Organized Nanolayers Of Organosilane Molecules, Ocelio V. Lima Dec 2009

Self-Organized Nanolayers Of Organosilane Molecules, Ocelio V. Lima

Engineering Mechanics Dissertations & Theses

There is a high degree of interest in organic thin films for lightweight, low power, rugged and flexible electronics. Conjugated organic molecules with polycyclic rings are being considered a major enabler of such applications. Due to a surface tension mismatch between the organic molecule with the inorganic support (mainly silicon oxides), molecular packing inside these thin films is often disordered, which suppresses the device performance. There are major efforts focused on modifying the bulk properties, for instance, maximizing orbital overlaps in the solid state, little attention was paid to receive long-range ordered thin films. A novel approach to afford conjugated ...


Enhance Diamond Coating Adhesion By Oriented Interlayer Microcracking, Habio Guo, Xingcheng Xiao, Yue Qi, Zhi-Hui Xu, Xiaodong Li Dec 2009

Enhance Diamond Coating Adhesion By Oriented Interlayer Microcracking, Habio Guo, Xingcheng Xiao, Yue Qi, Zhi-Hui Xu, Xiaodong Li

Faculty Publications

In this paper, we report a microcrack toughening mechanism for enhancing the adhesion of diamondcoating. The oriented microcracks were formed within the TiC interlayer to dissipate strain energy and accommodate deformation via the crack opening-closing mechanism, thus enhancing the coating/substrate interfacial toughness. The delamination of diamondcoating was effectively prevented when the parallel microcracks were confined within the interlayer and arrested at interfaces of coating/interlayer/substrate. Density functional theory calculations revealed that the highly anisotropicfracture strength of the TiC phase energetically favors crack initiation and propagation along (100) planes only, which are 54.7° away from the interface. These ...


Development Of A Methodology For Numerical Simulation Of A D C Arc Discharge In A Liquid Dielectric, Christopher James Lewis Dec 2009

Development Of A Methodology For Numerical Simulation Of A D C Arc Discharge In A Liquid Dielectric, Christopher James Lewis

Theses and Dissertations

The majority of literature regarding the numerical simulation of arc discharges in gaseous environments has used a plasma physics approach. Virtually all simulations treat the discharge as an idealized gaseous plasma, which can be described by temperature, pressure, and electric field. This approach can work well if the media is a shielding gas such as Argon; however, the approach does not work well for processes such as underwater welding, EDM, and underwater discharges used to generate high purity particles. The reason these discharges do not have many extensive simulation efforts as described in the literature is because they occur in ...


Energy Dissipation Caused By Asphalt Roadway Gouges For Use In Accident Reconstruction, Charles L. Crosby Dec 2009

Energy Dissipation Caused By Asphalt Roadway Gouges For Use In Accident Reconstruction, Charles L. Crosby

Theses and Dissertations

In reconstruction of on-roadway vehicle accidents, roadway surface gouges and the forces and energy attributed to the related vehicle components become important keys to resolving an accurate accident reconstruction. These roadway gouge forces vary depending upon such factors as surface temperature and the velocity and geometry of the gouging mechanism. Accounting for the forces applied to vehicle components and the energy dissipated from such forces can be helpful in accident reconstruction where supporting data exists. This research documents the force necessary to create a given roadway gouge geometry. Controlled pavement gouging tests were performed using roadway surface temperature and gouging ...


Discrete Film Cooling In A Rocket With Curved Walls, Jonathan F. Mccall Dec 2009

Discrete Film Cooling In A Rocket With Curved Walls, Jonathan F. Mccall

Theses and Dissertations

This study quantified the effects of discrete wall-based film cooling in a rocket with curved walls. Simulations and experiments showed decreasing with wall radius of curvature, holding jet diameter constant, improves net heat flux reduction (NHFR) and adiabatic effectiveness (η) for 90˚ compound injected cylindrical jets, though η is reduced at the highest curvature. NHFR and η improved further with a high favorable stream-wise pressure gradient (K=2.1x10-5) at all tested blowing ratios, but were affected little by a high density ratio (DR=1.76) using carbon dioxide as the coolant. Experiments were run at a Reynolds number ...


Investigation Into Contact Resistance And Damage Of Metal Contacts Used In Rf-Mems Switches, Kevin W. Gilbert Dec 2009

Investigation Into Contact Resistance And Damage Of Metal Contacts Used In Rf-Mems Switches, Kevin W. Gilbert

Theses and Dissertations

This research examines the physical and electrical processes involved in lifecycle failure of Microelectromechanical (MEMS) Radio-Frequency (RF) cantilever beam ohmic contact switches. Failures of these switches generally occur at the contact, but complete details of performance of microcontacts are difficult to measure and have not been previously reported. This study investigated the mechanics of microcontact behavior by designing and constructing a novel experimental setup. Three representative contact materials of varying microstructure (Au, Au5%Ru, Au4%V2O5) were tested and parameters of contact during cycling were measured. The Au4%V2O5, a dispersion strengthened material developed ...


Optical Properties Of Semiconducting Boron Carbide For Neutron Detection Applications, Ravi B. Billa Dec 2009

Optical Properties Of Semiconducting Boron Carbide For Neutron Detection Applications, Ravi B. Billa

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

Solid state neutron detection devices based on semiconducting boron carbide have the potential for nearly ideal neutron detection effciency for thermal neutrons. The present work is focused on characterizing optical properties of this semiconducting boron carbide material as a step in further development of the material for neutron detection and other applications.

Semiconducting boron carbide films were grown on silicon substrates using plasma enhanced chemical vapor deposition and their optical properties were characterized using variable angle spectroscopic ellipsometry over a wide spectral range, from mid-infrared to vacuum-ultraviolet wavelengths. The effects of deposition substrate temperature and of post-deposition heat treatments on ...


College Of Engineering Senior Design Competition Fall 2009, University Of Nevada, Las Vegas Dec 2009

College Of Engineering Senior Design Competition Fall 2009, University Of Nevada, Las Vegas

Senior Projects (COE)

Each student in his or her senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. The senior design project encourages the student to use everything learned in the engineering program to create a practical, real-world solution to an engineering challenge.

A highlight of the year-long senior design project is the senior design competition. This competition, which usually takes place the week before finals each semester, helps focus the senior students on increasing the quality and potential for commercial application for their design projects.

Judges from local industry evaluate the projects on innovation, commercial ...


Study Of Take-Up Velocity In Enhancing Tensile Properties Of Aligned Electrospun Nylon 6 Fibers, Johnny F. Najem Dec 2009

Study Of Take-Up Velocity In Enhancing Tensile Properties Of Aligned Electrospun Nylon 6 Fibers, Johnny F. Najem

Mechanical Engineering Faculty Research

The variation of both the tensile properties and thermal properties of aligned electrospun fibers with the take-up velocity (TUV) of disc collector has not been widely investigated due to the difficulty of handling aligned nanofibers and measuring low loads. In this thesis, 25% of nylon 6 was dissolved in formic acid and then electrospun into fibers and the fibers were aligned using a rotating disc collector. We evaluated the tensile and thermal properties, average fiber diameter, crystallinity, crystalline morphology, molecular and crystalline orientation of aligned electrospun nylon 6 nanofibers as a function of TUV based on a disc collector. It ...


Direct Cooled Ceramic Substrate For Thermal Control Of Automotive Power Electronics, Kirk Townsend Lowe Dec 2009

Direct Cooled Ceramic Substrate For Thermal Control Of Automotive Power Electronics, Kirk Townsend Lowe

Doctoral Dissertations

As electric vehicle technology develops, manufacturers would like to move toward hotter coolants for power electronic components to reduce system level costs. Thus, unique designs of inverter designs were sought to enable operation with 105°C coolant. The proposed solution in this research incorporated flow channels into the ceramic layer of the direct-bonded copper substrate typically found in power electronic packages. The focus of this research details the design and analysis of the direct cooled ceramic substrate from the perspective of its thermal performance and innovative packaging concept.

The research was directed to pursue alumina as the substrate ceramic because ...


Thermodynamically Consistent Large Deformation Constitutive Model For Glassy Polymers, Ashwani Kumar Goel Dec 2009

Thermodynamically Consistent Large Deformation Constitutive Model For Glassy Polymers, Ashwani Kumar Goel

Engineering Mechanics Dissertations & Theses

Polycarbonate(PC), like most glassy polymers when undergoing large deformations exhibits a very complex thermo-mechanical response. We look at PC as a model glassy polymer and examine its response to changes in loading rate, loading direction and temperature. We show that plastic flow in compression is accompanied by a change in the elastic response of PC from isotropic to anisotropic. This provides the necessity to introduce a new modeling method that can capture these changes. A finite deformation plasticity like thermodynamically consistent model is developed to capture this and the observed rate and temperature dependence. For this modeling method, we ...


Me-Em Enewsbrief, December 2009, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University Dec 2009

Me-Em Enewsbrief, December 2009, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical Engineering-Engineering Mechanics eNewsBrief

No abstract provided.


Fabrication Of Layer-By-Layer Photonic Crystals Using Two Polymer Microtransfer Molding, Jae Hwang Lee, Kai-Ming Ho, Yong-Sung Kim, Kristen P. Constant, Chang-Hwan Kim Dec 2009

Fabrication Of Layer-By-Layer Photonic Crystals Using Two Polymer Microtransfer Molding, Jae Hwang Lee, Kai-Ming Ho, Yong-Sung Kim, Kristen P. Constant, Chang-Hwan Kim

Iowa State University Patents

A method of manufacturing photonic band gap structures operable in the optical spectrum has been presented. The method comprises the steps of filling a plurality of grooves of an elastomeric mold with a UV curable first polymer, each groove in parallel with each other and partially curing the first polymer. A second polymer is coated on the first polymer. A substrate or a multi-layer polymer structure is placed on the filled mold and the resulting structure is exposed to UV light (i.e., is UV cured). The mold is peeled away from the first and second polymers such that a ...


Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner Dec 2009

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mikhail Khenner

A mathematical model for the evolution of pulsed laser-irradiated, molten metallic films has been developed using the lubrication theory. The heat transfer problem that incorporates the absorbed heat from a single laser beam or the interfering laser beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the reflectivity, the peak laser beam ...


Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner Dec 2009

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mathematics Faculty Publications

A mathematical model for the evolution of pulsed laser-irradiated, molten metallic films has been developed using the lubrication theory. The heat transfer problem that incorporates the absorbed heat from a single laser beam or the interfering laser beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the reflectivity, the peak laser beam ...


Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner Dec 2009

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mathematics Faculty Publications

A mathematical model for the evolution of pulsed laser-irradiated, molten metallic films has been developed using the lubrication theory. The heat transfer problem that incorporates the absorbed heat from a single laser beam or the interfering laser beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the reflectivity, the peak laser beam ...


Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner Dec 2009

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mathematics Faculty Publications

A mathematical model for the evolution of pulsed laser-irradiated, molten metallic films has been developed using the lubrication theory. The heat transfer problem that incorporates the absorbed heat from a single laser beam or the interfering laser beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the reflectivity, the peak laser beam ...


Gender Dimorphic Acl Strain In Response To Combined Dynamic 3d Knee Joint Loading: Implications For Acl Injury Risk, Kiyonori Mizuno, Jack T. Andrish, Antonie J. Van Den Bogert, Scott G. Mclean Dec 2009

Gender Dimorphic Acl Strain In Response To Combined Dynamic 3d Knee Joint Loading: Implications For Acl Injury Risk, Kiyonori Mizuno, Jack T. Andrish, Antonie J. Van Den Bogert, Scott G. Mclean

Mechanical Engineering Faculty Publications

While gender-based differences in knee joint anatomies/laxities are well documented, the potential for them to precipitate gender-dimorphic ACL loading and resultant injury risk has not been considered. To this end, we generated gender-specific models of ACL strain as a function of any six degrees of freedom (6DOF) knee joint load state via a combined cadaveric and analytical approach. Continuously varying joint forces and torques were applied to five male and five female cadaveric specimens and recorded along with synchronous knee flexion and ACL strain data. All data (~10,000 samples) were submitted to specimen-specific regression analyses, affording ACL strain ...


Optimization-Based Dynamic Prediction Of 3d Human Running, Hyun-Joon Chung Dec 2009

Optimization-Based Dynamic Prediction Of 3d Human Running, Hyun-Joon Chung

Theses and Dissertations

Mathematical modeling of human running is a challenging problem from analytical and computational points of view. Purpose of the present research is to develop and study formulations and computational procedures for simulation of natural human running. The human skeletal structure is modeled as a mechanical system that includes link lengths, mass moments of inertia, joint torques, and external forces. The model has 55 degrees of freedom, 49 for revolute joints and 6 for global translation and rotation. Denavit-Hartenberg method is used for kinematics analysis and recursive Lagrangian formulation is used for the equations of motion. The dynamic stability is achieved ...


Experimental Investigation Of Free Dendritic Growth Of Succinonitrile-Acetone Alloys, Antonio Jose Melendez Ramirez Dec 2009

Experimental Investigation Of Free Dendritic Growth Of Succinonitrile-Acetone Alloys, Antonio Jose Melendez Ramirez

Theses and Dissertations

Measurements are carried out for dendrite tip growth of succinonitrile-acetone alloys solidifying freely in an undercooled melt. The current experimental investigation is conducted using the equiaxed dendritic solidification experiment (EDSE). This setup allows for precise measurements of the dendrite tip velocity, radius and shape for a range of undercoolings and solute concentrations. The collected data are compared to available theories of free dendritic growth, such as the Lipton-Glicksman-Kurz and Li-Beckermann models. It is found that for dilute succinonitrile-acetone alloys, the measured dendrite tip Péclet numbers agree well with previous theories of free dendritic growth, if the effects of melt convection ...


Computational Fluid Dynamics Modeling Of Atmospheric Flow Applied To Wind Energy Research, Alan Russell Dec 2009

Computational Fluid Dynamics Modeling Of Atmospheric Flow Applied To Wind Energy Research, Alan Russell

Boise State University Theses and Dissertations

High resolution atmospheric flow modeling using computational fluid dynamics (CFD) has many applications in the wind energy industry. A well designed model can accurately calculate wind speed, direction, and turbulence at any point in a wind farm using data from a fixed location source. The model can extend point source data over an area of several square kilometers, or map terrain influenced microclimates using remote wind data. A local flow model is critical for wind resource site assessment, and for optimizing wind farm turbine layout for maximum power production. A CFD simulation of an operating wind farm, coupled with a ...


Cfd Prediction Of Ship Capsize: Parametric Rolling, Broaching, Surf-Riding, And Periodic Motions, Seyed Hamid Sadat Hosseini Dec 2009

Cfd Prediction Of Ship Capsize: Parametric Rolling, Broaching, Surf-Riding, And Periodic Motions, Seyed Hamid Sadat Hosseini

Theses and Dissertations

Stability against capsizing is one of the most fundamental requirements to design a ship. In this research, for the first time, CFD is performed to predict main modes of capsizing. CFD first is conducted to predict parametric rolling for a naval ship. Then CFD study of parametric rolling is extended for prediction of broaching both by using CFD as input to NDA model of broaching in replacement of EFD inputs or by using CFD for complete simulation of broaching. The CFD resistance, static heel and drift in calm water and static heel in following wave simulations are conducted to estimate ...


Boundary Layer Data System (Blds) Heating System, John Hauge, Drew Hutcheson, Paul Scott Dec 2009

Boundary Layer Data System (Blds) Heating System, John Hauge, Drew Hutcheson, Paul Scott

Mechanical Engineering

The boundary layer data system (BLDS) is the result of a collaborative effort between Dr. Westphal, a researcher and instructor at Cal Poly, and Northrop Grumman. The BLDS is capable of measuring the boundary layer profile and characteristics of flow over aerodynamic surfaces and is intended for high altitude, high speed use. The instruments inside the BLDS malfunction at the low temperatures present when operating in flight at altitudes above 30,000 ft. To solve this problem, analysis was done on the existing BLDS which determined the heating requirements, around 50 watts, needed to keep the internal temperature within the ...