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Articles 601 - 619 of 619

Full-Text Articles in Mechanical Engineering

The Characterization Of Aerosol Particle Contamination As The Result Of Carry-Over And Cross-Over In Enthalpy Wheels, Rodney G. Handy, Kevin Rodgers, Jon Wang, Matt Tumey, Danny Rodriguez, William J. Hutzel Jan 2010

The Characterization Of Aerosol Particle Contamination As The Result Of Carry-Over And Cross-Over In Enthalpy Wheels, Rodney G. Handy, Kevin Rodgers, Jon Wang, Matt Tumey, Danny Rodriguez, William J. Hutzel

School of Engineering Technology Faculty Publications

This paper provides results from a study that characterized the particle distributions found from variable contaminated airstreams in energy recovery ventilators (ERV) during two different test scenarios. The first scenario involved the measurement of the particulate concentrations during an operational situation when the pressure differential forces cross-flow leakage between the exhaust and intake streams. The second scenario involved the characterization of aerosol particulate concentrations from the carry-over contamination when the wheel was not in operation. The findings from the study concluded that if a source of aerosol particulate matter is present in an environment utilizing an ERV system, then cross-over …

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Strain Energy And Lateral Friction Force Distributions Of Carbon Nanotubes Manipulated Into Shapes By Atomic Force Microscopy, Mark C. Strus, Roya R. Lahiji, Pablo Ares, Vincente Lopez, Arvind Raman, Ron R. Reifenberger Aug 2009

Strain Energy And Lateral Friction Force Distributions Of Carbon Nanotubes Manipulated Into Shapes By Atomic Force Microscopy, Mark C. Strus, Roya R. Lahiji, Pablo Ares, Vincente Lopez, Arvind Raman, Ron R. Reifenberger

Other Nanotechnology Publications

The interplay between local mechanical strain energy and lateral frictional forces determines the shape of carbon nanotubes on substrates. In turn, because of its nanometer-size diameter, the shape of a carbon nanotube strongly influences its local electronic, chemical, and mechanical properties. Few, if any, methods exist for resolving the strain energy and static frictional forces along the length of a deformed nanotube supported on a substrate. We present a method using nonlinear elastic rod theory in which we compute the flexural strain energy and static frictional forces along the length of single walled carbon nanotubes (SWCNTs) manipulated into various shapes …

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Interfacial Energy Between Carbon Nanotubes And Polymers Measured From Nanoscale Peel Tests In The Atomic Force Microscope, Mark C. Strus, Camilo I. Cano, R. Byron Pipes, Cattien V. Nguyen, Arvind Raman Mar 2009

Interfacial Energy Between Carbon Nanotubes And Polymers Measured From Nanoscale Peel Tests In The Atomic Force Microscope, Mark C. Strus, Camilo I. Cano, R. Byron Pipes, Cattien V. Nguyen, Arvind Raman

Other Nanotechnology Publications

The future development of polymer composite materials with nanotubes or nanoscale fibers requires the ability to understand and improve the interfacial bonding at the nanotube-polymer matrix interface. In recent work [Strus MC, Zalamea L, Raman A, Pipes RB, Nguyen CV, Stach EA. Peeling force spectroscopy: exposing the adhesive nanomechanics of one-dimensional nanostructures. Nano Lett 2008;8(2):544–50], it has been shown that a new mode in the Atomic Force Microscope (AFM), peeling force spectroscopy, can be used to understand the adhesive mechanics of carbon nanotubes peeled from a surface. In the present work, we demonstrate how AFM peeling force spectroscopy can be …

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Identification Of Multiple Oscillation States Of Carbon Nanotube Tipped Cantilevers Interacting With Surfaces In Dynamic Atomic Force Microscopy, Mark Strus, Arvind Raman Jan 2009

Identification Of Multiple Oscillation States Of Carbon Nanotube Tipped Cantilevers Interacting With Surfaces In Dynamic Atomic Force Microscopy, Mark Strus, Arvind Raman

Birck and NCN Publications

Carbon nanotubes (CNTs) have gained increased interest in dynamic atomic force microscopy (dAFM) as sharp, flexible, conducting, nonreactive tips for high-resolution imaging, oxidation lithography, and electrostatic force microscopy. By means of theory and experiments we lay out a map of several distinct tapping mode AFM oscillation states for CNT tipped AFM cantilevers: namely, noncontact attractive regime oscillation, intermittent contact with CNT slipping or pinning, or permanent contact with the CNT in point or line contact with the surface while the cantilever oscillates with large amplitude. Each state represents fundamentally different origins of CNT-surface interactions, CNT tip-substrate dissipation, and phase contrast …

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The Effect Of Polydispersivity On The Thermal Conductivity Of Particulate Thermal Interface Materials, Sasanka Kanuparthi, Ganesh Subbarayan, Thomas Siegmund, Bahgat Sammakia Jan 2009

The Effect Of Polydispersivity On The Thermal Conductivity Of Particulate Thermal Interface Materials, Sasanka Kanuparthi, Ganesh Subbarayan, Thomas Siegmund, Bahgat Sammakia

School of Mechanical Engineering Faculty Publications

A critical need in developing thermal interface materials (TIMs) is an understanding of the effect of particle/matrix conductivities, volume loading of the particles, the size distribution, and the random arrangement of the particles in the matrix on the homogenized thermal conductivity. Commonly, TIM systems contain random spatial distributions of particles of a polydisperse (usually bimodal) nature. A detailed analysis of the microstructural characteristics that influence the effective thermal conductivity of TIMs is the goal of this paper. Random microstructural arrangements consisting of lognormal size-distributions of alumina particles in silicone matrix were generated using a drop-fall-shake algorithm. The generated microstructures were …

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An Efficient Network Model For Determining The Effective Thermal Conductivity Of Particulate Thermal Interface Materials, S Kanuparthi, G Subbarayan, Thomas Siegmund, B Sammakia Jan 2008

An Efficient Network Model For Determining The Effective Thermal Conductivity Of Particulate Thermal Interface Materials, S Kanuparthi, G Subbarayan, Thomas Siegmund, B Sammakia

School of Mechanical Engineering Faculty Publications

Particulate composites are commonly used in Microelectronics applications. One example of such materials is Thermal Interface Materials (TIMs) that are used to reduce the contact resistance between the chip and the heat sink. The existing analytical descriptions of thermal transport in particulate systems do not accurately account for the effect of inter-particle interactions, especially in the intermediate volume fractions of 30-80%. Another crucial drawback in the existing analytical as well as the network models is the inability to model size distributions (typically bimodal) of the filler material particles that are obtained as a result of the material manufacturing process. While …

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Determination Of Superior Surface Strains And Stresses, And Vocal Fold Contact Pressure In A Synthetic Larynx Model Using Digital Image Correlation, Mychal Spencer, Thomas Siegmund, Luc Mongeau Jan 2008

Determination Of Superior Surface Strains And Stresses, And Vocal Fold Contact Pressure In A Synthetic Larynx Model Using Digital Image Correlation, Mychal Spencer, Thomas Siegmund, Luc Mongeau

School of Mechanical Engineering Faculty Publications

No abstract provided.

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A Two-Layer Composite Model Of The Vocal Fol Lamina Propria For Fundamental Frequency Regulation, Kai Zhang, Thomas Siegmund, Roger W. Chan Jan 2007

A Two-Layer Composite Model Of The Vocal Fol Lamina Propria For Fundamental Frequency Regulation, Kai Zhang, Thomas Siegmund, Roger W. Chan

School of Mechanical Engineering Faculty Publications

No abstract provided.

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Thermally Developing Flow And Heat Transfer In Rectangular Microchannels Of Different Aspect Ratios, Poh-Seng Lee, S V. Garimella Feb 2006

Thermally Developing Flow And Heat Transfer In Rectangular Microchannels Of Different Aspect Ratios, Poh-Seng Lee, S V. Garimella

CTRC Research Publications

Laminar convective heat transfer in the entrance region of microchannels of rectangular cross-section is investigated under circumferentially uniform wall temperature and axially uniform wall heat flux thermal boundary conditions. Three-dimensional numerical simulations were performed for laminar thermally developing flow in microchannels of different aspect ratios. Based on the temperature and heat flux distributions obtained, both the local and average Nusselt numbers are presented graphically as a function of the dimensionless axial distance and channel aspect ratio. Generalized correlations, useful for the design and optimization of microchannel heat sinks and other microfluidic devices, are proposed for predicting Nusselt numbers. The proposed …

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A Constitutive Model Of The Human Vocal Fold Cover For Fundamental Frequency Regulation, Kai Zhang, Thomas Siegmund, Roger W. Chan Jan 2006

A Constitutive Model Of The Human Vocal Fold Cover For Fundamental Frequency Regulation, Kai Zhang, Thomas Siegmund, Roger W. Chan

School of Mechanical Engineering Faculty Publications

No abstract provided.

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A Novel Hybrid Heat Sink Using Phase Change Materials For Transient Thermal Management Of Electronics, Shankar Krishnan, S V. Garimella, S. S. Kang Jun 2005

A Novel Hybrid Heat Sink Using Phase Change Materials For Transient Thermal Management Of Electronics, Shankar Krishnan, S V. Garimella, S. S. Kang

CTRC Research Publications

A hybrid heat sink concept which combines passive and active cooling approaches is proposed. The hybrid heat sink is essentially a plate fin heat sink with the tip immersed in a phase change material (PCM). The exposed area of the fins dissipates heat during periods when high convective cooling is available. When the air cooling is reduced, the heat is absorbed by the PCM. The governing conservation equations are solved using a finite-volume method on orthogonal, rectangular grids. An enthalpy method is used for modeling the melting/re-solidification phenomena. Results from the analysis elucidate the thermal performance of these hybrid heat …

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International Partnership Using Remotely Accessed Labs, William J. Hutzel, Rudolf Furter Jan 2005

International Partnership Using Remotely Accessed Labs, William J. Hutzel, Rudolf Furter

School of Engineering Technology Faculty Publications

An international project between the Mechanical Engineering Technology Department at Purdue University and the HVAC Engineering Department at HTA Lucerne (Switzerland) is testing the limits of the remote access concept by creating a laboratory network that is separated by thousands of miles. Using web-enabled HVAC equipment, U.S. students are determining the performance and return on investment for a heat recovery system that is physically located in Switzerland. The converse is also true, Swiss students have access to a variety of equipment located in the U.S. This remote access project is a good example of a sustainable partnership that adds an …

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Low Reynolds Number Flow Through Nozzle-Diffuser Elements In Valveless Micropumps, Vishal Singhal, Jayathi Y. Murthy, S V. Garimella Apr 2004

Low Reynolds Number Flow Through Nozzle-Diffuser Elements In Valveless Micropumps, Vishal Singhal, Jayathi Y. Murthy, S V. Garimella

CTRC Research Publications

Flow characteristics of low Reynolds number laminar flow through gradually expanding conical and planar diffusers were investigated. Such diffusers are used in valveless micropumps to effect flow rectification and thus lead to pumping action in one preferential direction. Four different types of diffuser flows are considered: fully developed and thin inlet boundary layer flows through conical and planar diffusers. The results from the numerical analysis have been quantified in terms of pressure loss coefficient. The variation of pressure loss coefficient with diffuser angle is presented for Reynolds numbers of 200, 500 and 1000. The pressure loss coefficients have been used …

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Optimization Of Thermal Interface Materials For Electronics Cooling Applications, Vishal Singhal, Thomas Siegmund, Suresh V. Garimella Jan 2004

Optimization Of Thermal Interface Materials For Electronics Cooling Applications, Vishal Singhal, Thomas Siegmund, Suresh V. Garimella

School of Mechanical Engineering Faculty Publications

Thermal interface materials (TIMs) are used in electronics cooling applications to decrease the thermal contact resistance between surfaces in contact. A methodology to determine the optimal volume fraction of filler particles in TIMs for minimizing the thermal contact resistance is presented. The method uses finite element analysis to solve the coupled thermo-mechanical problem. It is shown that there exists an optimal filler volume fraction which depends not only on the distribution of the filler particles in a TIM but also on the thickness of the TIM layer, the contact pressure and the shape and the size of the filler particles. …

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Remotely Accessible Solar Energy Laboratory For High School Students, William J. Hutzel, David Goodman Jan 2004

Remotely Accessible Solar Energy Laboratory For High School Students, William J. Hutzel, David Goodman

School of Engineering Technology Faculty Publications

A remotely accessible solar energy laboratory has been developed for real-time experimentation using solar heating and photovoltaic equipment that is physically located at Purdue University. Indiana high school students are the first customers for this on-line resource. In addition to sensor data, the web-based laboratory includes lesson plans, tutorials, assessment questions, and a feedback utility. This project is helping science teachers meet new state science standards from the Indiana Department of Education, which call for hands-on laboratory activities and real time data analysis. Remotely accessed labs are becoming popular because they offer the opportunity for large numbers of students to …

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A Comparative Analysis Of Studies On Heat Transfer And Fluid Flow In Microchannels, Choondal B. Sobhan, Suresh V. Garimella Apr 2001

A Comparative Analysis Of Studies On Heat Transfer And Fluid Flow In Microchannels, Choondal B. Sobhan, Suresh V. Garimella

CTRC Research Publications

The extremely high rates of heat transfer obtained by employing microchannels makes them an attractive alternative to conventional methods of heat dissipation, especially in applications related to the cooling of microelectronics. A compilation and analysis of the results from investigations on fluid flow and heat transfer in micro- and mini-channels and microtubes in the literature is presented in this review, with a special emphasis on quantitative experimental results and theoretical predictions. Anomalies and deviations from the behavior expected for conventional channels, both in terms of the frictional and heat transfer characteristics, are discussed.

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An Interdisciplinary Solar Energy Project, William J. Hutzel Jan 1996

An Interdisciplinary Solar Energy Project, William J. Hutzel

School of Engineering Technology Faculty Publications

An HVAC course, previously offered to students in Mechanical Engineering Technology (MET), has been re-structured to include students in Building Construction Management (BCM). A large project is always an integral part of this course, creating a unique opportunity for collaboration between two distinctly different groups of Technology students. This cooperation is particularly beneficial because MET and BCM graduates frequently cross paths during their professional careers. Many MET graduates operate and service heating, ventilating, and air conditioning equipment that was originally specified and installed by BCM graduates. This paper discusses and evaluates student interactions during a solar …

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Turbomachine Stability And Forced Response Prediction, Leland Bert Clark Dec 1992

Turbomachine Stability And Forced Response Prediction, Leland Bert Clark

Open Access Theses

A mathematical model is developed and utilized to analyze turbomachine cascade flutter and forced response. The flutter boundary, defined as the largest value of reduced frequency at which flutter occurs for a given cascade, was evaluated for single degree of freedom torsional oscillation as well as coupled bending and torsional oscillations. The maximum amplitude of forced response in bending and torsion was also considered. The unsteady aerodynamic lift and moment coefficients were determined from unsteady aerodynamic flow models for subsonic flow, supersonic flow with a subsonic axial component and supersonic axial flow. The effect of changing the Mach number, stagger …

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Experimental And Theoretical Studies On Design Calculations For Latent Heat Storage, Dieter Lindemann Jan 1987

Experimental And Theoretical Studies On Design Calculations For Latent Heat Storage, Dieter Lindemann

Open Access Theses

Research was conducted to obtain design data of latent heat-of-fusion thermal energy storage (LHTES) devices. The devices studied utilize a porous medium (PM) to increase the effective conductivity of the storage system. Therefore the melting and freezing process is accelerated. Metal shavings and metal spheres were used as porous media and water as the phase change medium (PCM). A simple experimental method to measure the conductivity of a water-metal mixture or ice-metal mixture was applied to obtain conductivity data. These measurements can be considered fairly accurate because measured conductivity of pure water and of pure ice agreed very well with …

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