M. Mehdi Salek
University of Calgary

Jake Askeland
San Jose State University

Abstract

The development of biofilms, colonies of microorganisms encased in a self-generated polysaccharide matrix, on medical devices and artery walls is associated with most nosocomial, chronic infections. Because biofilms are more resistance to antimicrobial agents when compared to the same bacteria in planktonic suspension, they pose a major challenge in clinical medicine. Different studies demonstrated that biofilm formation is strongly affected by the local hydrodynamic conditions: in particular, flow reversal and fluctuating near-wall conditions. A Backward Facing Step (BFS) channel is an in-vitro example to represent common types of flow conditions which occur frequently in different medical devices and arteries. The main objective of this study is to characterize the pulsatile flow over a BFS in terms of oscillation parameters. Biofilm characteristics will be examined in different regions of the flow to develop a model to discuss the influences of the flow patterns on the biofilm behavior.

M. Mehdi Salek
University of Calgary

Industrial research, practical application. Describes a hydraulic cyclic-loading mechanical Testing-Machine, designed for use in research in a corporate factory environment. Equipment and controls were selected for safety, adaptability to a variety of test set-up's, self-protection, easy replacement of components if damaged in a destructive Test-Center environment, and especially for use by smart but non-scientific factory personnel. Equipment was designed to shut-down automatically in a safe manner in the event of test-piece failure, equipment failure, or personal hazard. Presentation concludes with tips for getting transferred to the Corporate Research Department.

Scot MacEwan, P.E.
Bachelor of Science, Mechanical Engineering,
Oregon State University, 1967

Traditional product development efforts are based on well-structured and hierarchical product development teams. The product is systematically decomposed into subsystems that are designed by dedicated teams with well defined information flows. Recently, a new product development approach called Mass Collaborative Product Development (MCPD) has emerged. The fundamental difference between traditional product development processes and MCPD processes is that the former are based on top-down decomposition while the latter are based on evolution and self-organization. The paradigm of MCPD has resulted in highly successful products such as Wikipedia, Linux and Apache. Despite the success of MCPD, it is not well understood how the product architecture affects the rate at which the products evolve.

To address that research gap, an agent-based model to study the MCPD processes is presented in this paper. Through this model, the effect of product architecture on the product evolution is studied. By applying the Agent-Based Modeling (ABM), a computational model is built to simulate the MCPD processes. The model is executed for different mobile phone architectures ranging from slot architecture to bus architecture and the rates of product evolution are determined. The simulation-based approach allows us to study how the degree of modularity of products affects the evolution time of products and different components in the MCPD processes. The methodology is demonstrated using an example of design of mobile phones. This approach provides a simple and intuitive way to study the effects of product architecture on the MCPD processes. The approach is helpful in determining the best strategies for product decomposition and identifying the product architectures that are suitable for the MCPD processes.

Qize Le and Jitesh Panchal
Washington State University

Presenter: Kang Wang
University of Washington

A no-chamber solid-oxide fuel cell operated on a fuel-rich ethanol flame was reported. Heat produced from the combustion of ethanol thermally sustained the fuel cell at a temperature of 500-830 oC. Considerable amounts of hydrogen and carbon monoxide were also produced during the fuel-rich combustion which provided the direct fuels for the fuel cell. The location of the fuel cell with respect to the flame was found to have a significant effect on the fuel cell temperature and performance. The highest power density was achieved when the anode was exposed to the inner flame. By modifying the Ni+Sm0.2Ce0.8O1.9 (SDC) anode with a thin Ru/SDC catalytic layer, the fuel cell envisaged not only an increase of the peak power density to ~ 200 mW cm-2 but also a significant improvement of the anodic coking resistance.

Kang Wang
Jeongmin Ahn, Zongping Shao
Washington State University

Presenter: Abdul Rauf
University of Southern California

In last couple of years, Cubesats have emerged as extremely low-cost, small space platforms for science research missions. Apart from achieving scientific objectives, these "picosatellites" have paved the way for training new scientific and engineering students from different disciplines to play a pivotal role in future space technology. University of Southern California's Astronautics and Space Technology Division started it's first ever Cubesat project, "USCubesat" last year. Because of the fact that this new class of small spacecrafts is limited in terms of size and mass, the structural engineer has to make sure that the overall design and strength requirements can support very small components during all mission stages. In order to meet these requirements, an initial analysis is carried out on the configuration using different finite element based analysis tools such as Femap/NX Nastran. Since the analysis results are strongly dependent on modeling assumptions, i.e., the way we build and define our input model, we are investigating a method to tie the geometric model directly to the analysis inputs to allow a closed loop method to analyze the design in the shortest amount of time.

Abdul Rauf, (Author), David Barnhart (Advisor)
University of Southern California, Los-Angeles, CA
Department of Aerospace & Mechanical Engineering, Viterbi school of engineering

Presenter: Harish V Penmethsa
San Jose State University

Stacked die packaging techniques dramatically increase the density of interconnects and device functionally by allowing multiple dies to occupy the same area traditionally occupied by only one die. This project focuses on allowable stacked package overhang die deflection due to wire bonding force. The overhang die configuration is commonly observed in the stacked die packages where thin dies are either crossed when stacked or separated by a spacer. These configurations result in die edges that are not fully supported and are allowed to deflect during the wire bonding process. Computer simulations along with theoretical analysis are carried out to determine the allowable die overhang deflection due to wire bond force considering fracture damage to the die. In stacked die packages die overhang length, wire bond force and die thickness are considered as critical parameters. It is concluded that the die deflection should not exceed half the thickness of the spacer for the case of tower stacked dies as it would damage the wire loop profile of the bottom die. In general the spacer thickness is varied from 7 mils to 20 mils and the wire loop height is varied from 2.5 mils to 6 mils depending on the application and wire loop shape. Hence the deflection is limited to vary from 3.5 mils to 10 mils based on the application. Maximum stress in the die should not exceed the yield strength of the material. The allowable deflection for a rotated stacked silicon die with dimensions 10x5 mm, overhang length 2.5 mm, thickness 0.1 mm and wire bond force of 15 grams is 1.955x10-5 m. Furthermore, it is concluded that increasing the overhang length increases the stacked die deflection for a fixed thickness.

Author: Harish V Penmethsa, Advisor: Dr Fred Barez
San Jose State University, Mechanical and Aerospace Department

Presented by: Pavan Kumar Murukutla
San Jose State University

As the electronic equipment become small and smaller in size the power and circuit densities increase which results in the generation of significant amounts of Electro Magnetic Interference (EMI) and thermal loads. EMI is low frequency, low-impedance radiated electro-magnetic waves that could impair circuit performance inside an Integrated Circuit (IC) package, cabling systems or an electronic enclosure. EMI could leak through unshielded enclosures or a cooling vent or opening to disrupt the operation of the near by electronic equipment. This study focuses on shielding effectiveness in enclosures due to dual cooling vent screen. The enclosure is considered to be 300 mm wide x 300 mm deep x 120 mm height, with an input source of 0-1 GHz frequency. This work is carried out through analytical and computer simulation using available software to benchmark and to study the effect of dual screens with various geometries. The study concluded that use of dual screens 40 mm apart with back to back hexagonal apertures provides the most effective EMI shielding by as much as 22.8 % as compared to a single screen with similar size, shape and number of apertures. Furthermore, an offset of 60 mm between the apertures on the dual screens will improve the shielding effectiveness by 13 %.

Pavan Kumar Murukutla
San Jose State University

Presented by: Jake Askeland
San Jose State University

Finding shortest paths between all pairs of vertices in a sparse graph has an inherent runtime on the order of O(V^2 log V + VE) (Johnson's algorithm). For large topological maps, this can take extraordinary amounts of CPU time and system resources to compute. The algorithm being presented minimizes the vertices needed in a topological map by fitting an approximately minimal set of convex polygons and removing vertices not used by two or more polygons.

Jake Askeland
San Jose State University

Presented by: Benson Sit
San Jose State University

The prognosis of an illness is often brighter with early detection and proper treatment. Early detection allows medical providers to act before a disease worsens. For example, the mortality rate for hydrocephalus (rapid head growth) has improved from 54% to 5% in the past 25 years. This has been attributed to advancements in the improvement of screening technologies such as CT and MRI. With early and accurate diagnosis, damage to the brain can be minimized allowing the patient to lead a more normal life. Current methods used to detect skull abnormalities are either expensive, time consuming or not always accurate. The purpose of this project is to develop a method to provide an accurate, repeatable, and reproducible measurement at an affordable price. It will use ultrasonic sensors to locate points on the head. With these points, a 2-dimensional shape of the head can be generated using spline curves. By computing the total length of the spline curves, the head circumference can be obtained. The head circumference measurement will allow medical providers to screen for various skull abnormalities such as Hydrocephalus, Dandy-Walker syndrome, and Craniosynostosis for young children.

Benson Sit
San Jose State University

Presented by: Sreekanth Akarapu
Washington State University

The size dependent deformation of Cu single crystal micropillars with thickness ranging from 0.2 to 2.5 m subjected to uniaxial compression is investigated using a Multi-scale Discrete Dislocation Plasticity (MDDP) approach. MDDP is a hybrid elasto-visco plastic simulation model which couples discrete dislocation dynamics at the micro-scale (software micro3d) with the macroscopic plastic deformation. Our results show that the deformation field in these micropillars is heterogeneous from the onset of plastic flow and is confined to a few deformation bands, leading to the formation of ledges and stress concentrations at the surface of the specimen. Furthermore, the simulation yields a serrated stress-strain behavior consisting of discrete strain bursts that correlates well with experimental observations. The intermittent operation and stagnation of discrete dislocation arms is identified as the prominent mechanism that causes heterogeneous deformation and results in the observed macroscopic strain bursts. We show that the critical stress to bow an average minimum dislocation arm, whose length changes during deformation due to pinning events, is responsible for the observed size dependent response of the single crystals. We also reveal that hardening rates, similar to that shown experimentally, occur under relatively constant dislocation densities and are linked to dislocation stagnation due to the formation of entangled dislocation configuration and pinning sites.

S Akarapu
Washington State University

Presented by: I. Salehinia
Washington State University

Carbon nanotubes (CNTs) are promising materials for the creation of novel nanodevices. The weak van der Waals interaction between the walls of a double-walled carbon nanotube (DWCNT) allows for an easy slide and rotation of the tubes with respect to one another. This property provides a possibility to construct a new family of mechanical nanodevices where the nanometer scale motion is the relative sliding, rotation or bolt-nut motion of nanotube walls.
In this work, molecular modeling method is used to study the bolt-nut behavior in DWCNTs. This behavior originates from the chirality of the DWCNT walls. The result of this feature is the transmission between the linear and rotational motion, making the nanotube behaves like a bolt-nut pair.
There are a few rules currently available in the literature that determine the bolt-nut behavior of DWCNTs. However, those rules are rather contradictory and have been formulated for several specific kinds of DWCNTs. In this work, more general rules for linear-rotational transmission mechanisms which predict behavior for various pairs of DWCNTs are outlined.
By studying different DWCNTs, it is found that for a given outer wall tube, there are six preferred directions of motion that are defined by the chirality of the inner nanotube. These preferred directions coincide with zig-zag and arm-chair directions of the inner tube. The rotation of the inner tube occurs along one of these directions. However, the actual direction of rotation is detrmined by chirality of the outer tube.

I. Salehinia, S. N. Medyanik
Washington State University

Presented by: Roy Strandberg
University of Alaska Fairbanks

Nanofluids are colloidal dispersions of extremely small particles (with characteristic dimensions of 100 nm or less) in a base fluid. Research in recent years have shown that nanofluids with metallic particles have superior thermal conductivity and heat transfer properties compared to their respective base fluid. This comes at a cost of higher viscosity with increasing nanoparticle concentrations. In order to determine if the use of nanofluids in liquid heat transfer devices yields improved system performance, detailed theoretical analyses were performed. Finned tube radiators and air heating coils are two types of devices commonly employed in building comfort heating systems. The performance of these devices is characterized with Al2O3 nanoparticles in a base fluid of 60:40 ethylene glycol and water mixture by mass, which is most commonly used in cold regions. Based on the analyses, the use of Al2O3 nanofluid improves the heating capacity of finned tube radiators by 6.1% under certain conditions when compared to the finned tube radiator circulated with the base fluid. The Al2O3 nanofluid improves the capacity of a heating coil by 16.6% under certain conditions compared to the same coil circulated with the base fluid. For both types of devices, the analyses show that, for the same amount of heat transfer, the required volumetric flow rate using nanofluid is less than that of the base fluid. This results in lower pumping power than that required by the base fluid, despite the higher viscosity of nanofluid.

Roy Strandberg,
Dr. Debendra K. Das (Advisor)
University of Alaska Fairbanks

Presented by: Vamshi K. Avadhanula
University of Alaska Fairbanks

A 125 kW diesel engine-generator set was tested at the Energy Center of the University of Alaska Fairbanks for waste heat recovery from the exhaust gas, which was near a temperature of 540oC. A computer program was developed to determine how much heat can be recovered from the exhaust by a gas to liquid heat exchanger. This program was developed on Visual Basic for Application (VBA) in Microsoft Excel. Using the software one can calculate the heat exchanger surface area, pumping power required, cost estimates of the system and perform an economic analysis of the exhaust heat recovery system based on the amount of heat recovered and fuel prices. Both conventional heat transfer fluid, e.g., ethylene glycol/water mixture (60:40 by mass) and nanofluids were considered in the analysis. The program was run for CuO nanofluid of 2, 4 and 6 % particle volumetric concentration. Calculations showed that CuO nanofluid of 6 % particle volumetric concentration required 5.4 % less heat exchanger surface area and 6.8 % less cost of heat exchanger compared to ethylene glycol/water mixture. Computations with SiO2, Al2O3 and CuO nanofluids of 6 % particle volumetric concentration required 2.5, 4.6 and 5.4 % less heat exchanger surface area respectively, when compared to the ethylene glycol/water mixture.

Vamshi K. Avadhanula,
Co-Advisors: Dr. Debendra K. Das and Dr. Chuen-Sen Lin
University of Alaska Fairbanks