bluuebunny/crossref_metadata_2025 huggingface dataset:
An Information-Exchange Tool for Capturing and Communicating Decisions During Early-Phase Design and Concept Evaluation
Authors: Mehr Ali Farhang , Tumer Irem Y. , Barrientos Francesca , Ullman David
Published: April 2008

Capturing and communicating risk and uncertainty for NASA’s low-volume high-cost exploration missions have become the subject of intensive research in the past few years. As a result, a variety of quantitative and qualitative methodologies were developed, some of which have been adopted and implemented by various NASA centers in the form of risk management tools, procedures, or guidelines. Most of these methodologies, however, aim at the later stages of the design process or during the operational phase of the mission and therefore, are not applicable to the earlier stages of design. In practice, however, uncertainties in the decisions made during the early stages of design introduce a significant amount of risk to the concepts that are being evaluated. In this paper, we aim to capture and quantify uncertainty and risk due to the lack of knowledge as well as those associated with potential system failures. We present an information exchange tool (X-Change) that enables various subsystem designers to capture, quantify, and communicate the uncertainties due to their lack of knowledge as well as those due to failures that might not be readily available or easily-quantifiable. A key piece in this work is to incorporate risk and uncertainty due to the lack of knowledge during the early design phase, and combining it with the potential failure modes. The challenges we face in accomplishing this goal are: 1) lack of a unified ontology defining risk, uncertainty and failure in order to enable their use on common grounds; 2) difficulty in expressing and capturing risk and uncertainty due to the designers’ lack of knowledge at the early stages of design; 3) difficulty in accounting for potential failure modes and their associated risks at the functional design level, before a form or solution has been determined. In order to address these challenges, this paper first attempts to provide a definition for risk and uncertainty. Then, we present the results of an ongoing effort to develop a risk-based design tool for the concurrent mission design environment at NASA. We propose a framework that enables multiple subsystems to capture and communicate the relevant risk and uncertainty in their decisions. The application of the proposed framework is further elaborated using a satellite design example.
SprayCool™ Thermal Management for Dense Stacked Memory
Authors: Cader Tahir , Tollman Ben , Kabrell Cai , Krishnan Sridhar
Published: April 2008

The demand for increased computational power is continuing at an unrelenting pace. To meet this demand, board vendors are forced to increase the density of their systems. For example, some vendors today offer 1U servers with four processor motherboards. Accompanying this demand for increased computational power is an increasing demand for memory. With the introduction of multi-core microprocessors, the demand for memory will increase further. Traditional air-cooled memory modules, i.e., DIMMs, are increasingly consuming greater levels of motherboard real estate. In addition, rising internal system ambient temperatures are leading to increased failures of the memory, hard drives, power FETs, and other motherboard devices. This combination of events has created an opportunity for dense stacked memory that can either be air-cooled in nominal densities, or liquid-cooled in more extreme densities. The authors have designed, built, and are in the process of testing a dense dual Opteron board. The board conforms to the CompactPCI standard (6U × 160 mm), and houses four mezannine cards that can host up to 4 GB of dense stacked memory apiece (total of 16 GB for the board). The stacked memory is built using 512 Mb die, and is deployed in stacks of 8 and 10. The board is housed in a global SprayCool™ chassis that utilizes a dielectric fluid to cool all components on the board. As part of the development of the board, the design entailed CFD simulations of the full board, including the memory mezannine cards. The CFD simulations show that the memory junction temperature of 100°C can be maintained via spraying the backside of the mezannine cards, and by delivering enough spray to achieve a heat transfer coefficient of 0.05 W/cm2-K. Heat transfer coefficients an order of magnitude higher than 0.05 W/cm2-K are readily achievable with spray evaporative cooling, leaving headroom for significantly denser memory packages. Results from the comparison of the CFD simulations of the mezzanine cards to experimental temperature measurements will be presented for a variety of environmental conditions. The benefits of stacked memory will also be discussed from the standpoint of reliability, board density, system density, and benchmark performance.
Fabrication and Characterization of Liquid and Gaseous Micro- and Nanojets
Authors: Naik Nisarga , Courcimault Christophe , Hunter Hanif , Berg John , Lee Jungchul , Naeli Kianoush , Wright Tanya , Allen Mark , Brand Oliver , Glezer Ari , King William
Published: April 2008

This paper reports on the fabrication and characterization of liquid and gaseous jets ejected from microfabricated nozzles with dimensions ranging from 500 nm to 12 μm. Unlike previous work reporting the fabrication of nano-orifices defined within the thickness of the substrates [1-4], the in-plane nanonozzles presented in this paper are designed to sustain the high pressures necessary to obtain substantial nanofluidic jet flows. This approach also allows important three-dimensional features of nozzle, channel and fluidic reservoir to be defined by design and not by fabrication constraints, thereby meeting important fluid-mechanical criteria such as a fully-developed flow. The shrinking jet dimensions demand new metrology tools to investigate their flow behavior. A laser shadowgraphy technique is used to visualize and image the jet flows. Micromachined heated and piezoresistive cantilevers are used to investigate the thrust and heat flux characteristics of the jets.
Radiative Properties for Fire Suppression Environments Using a Correlated-k Method
Authors: Godoy William F. , DesJardin Paul E.
Published: April 2008

This study uses the correlated-k (c-k) and Mie scattering theory to evaluate absorption and scattering properties of participating media for fire suppression environments. In this approach the irregular spectral distribution of the radiative properties is reordered into cumulative distribution functions on a narrow band basis increasing the speed of property evaluation when compared to line-by-line calculations. The spectral properties are determined from the HITEMP database for carbon dioxide and water vapor, along with Mie and Rayleigh scattering theories for water droplets and soot particles, respectively. Results are presented for radiative heat transfer in a 1D domain for several mixtures and show that the attenuation of the radiation is highly sensitive to the water droplet size, mass loading and soot particle concentration.
A One-Dimensional Subgrid Near Wall Treatment forTurbulent Flow CFD Simulation
Authors: Myers Seth H. , Walters D. Keith
Published: April 2008

Prediction of the near wall region is crucial to the accuracy of turbulent flow computational fluid dynamics (CFD) simulation. However, sufficient near-wall resolution is often prohibitive for high Reynolds number flows with complex geometries, due to high memory and processing requirements. A common approach in these cases is to use wall functions to bridge the region from the first grid node to the wall. This paper presents an alternative method that relaxes the near wall resolution requirement by solving one dimensional transport equations for velocity and turbulent kinetic energy across a locally defined subgrid contained within wall adjacent grid cells. The addition of the subgrid allows for wall adjacent primary grid sizes to vary arbitrarily from low-Re model sizing (y+≈1) to wall function sizing without significant loss of accuracy or increase in computational cost. The method is applied to zero pressure gradient flow over a flat plate and yields solutions comparable to low-Re modeling with high near-wall resolution. Unlike low-Re or wall function modeling, the new method is shown to be insensitive to size variations of the first primary grid cell.
Florida’s First Coast Manufacturing Innovation Partnership Between Industry and Academia
Authors: Cox D. , Schonning A.
Published: April 2008

Joint industry-academia projects with regional industry have influenced creation of Florida’s First Coast Manufacturing Innovation Partnership (MIP). The development of MIP has the primary goals of project-centered innovations for technology transfer, training the regional workforce with relevance to industry, and sustainability of technology transfer through creation of high-technology jobs. The region known as Florida’s First Coast is one of the fastest growing in the nation and has received recent acclaim as a top location for new and emerging businesses and industries to relocate or expand. The importance of manufacturing to the economy is crucial. Every individual and industry depends on manufactured goods. This sector continues to account for 14% of US GDP and 11% of total US employment. One way to help expand the regional industrial base is to develop a shared resource support facility in the fields of manufacturing engineering and design. The first objective of MIP is to stimulate transformation of knowledge in design and manufacturing occurring in the academic domain to applied research and development in industry. This is accomplished with project-centered innovations developed using a shared manufacturing and design resource. The second objective of MIP is to develop partnerships with additional academic institutions with the common goal of producing students whose education satisfies the needs of the regional workforce with scientific and technological training with relevance to industry. This also includes a mentorship facet to attract and retain engineering students for the future. The third objective is to implement MIP for long-term sustainability of technology transfer and creation of high-technology jobs in the manufacturing engineering and design professions. Technology tools for innovation in advanced manufacturing, for example, robotics and automation, modular robotics, advanced manufacturing process development, manufacturing systems modeling, and simulation; and advanced design, for example, computer aided engineering including finite element modeling, design analysis, and rapid prototyping are used in support of projects in partnership with regional industrial companies. Joint industry-academic projects require the integration of research and the technical need of the partnering company. A critical level of innovation is accomplished with the outcomes of projects while providing a distinguishing educational background for the engineering graduates. Several partnership projects have been initiated under the auspices of MIP. These projects with local industry are outlined and serve as a platform for new and emerging projects for joint mutually beneficial collaboration between industry and academia.
L-Spline Finite Elements
Authors: Richter C. C. , Heppler G. R.
Published: April 2008

The L-spline finite element method is applied to the static deflection analysis and linear vibration analysis of curved Euler-Bernoulli and Timoshenko beams. A formal definition of membrane locking is presented along with a simple test that allows a priori determination of an L-spline finite element models susceptibility to locking. Formulations for both types of beam models, that under certain discretizations experience locking are presented. Examples that demonstrate the efficacy of the locking test and illustrate the L-spline finite element method performance are included.
Simulating Nanoscale Processes in Solids Using DFT and the Quasicontinuum Method
Authors: Negrut Dan , Anitescu Mihai , Munson Todd , Zapol Peter
Published: April 2008

A framework is proposed for the investigation of chemical and mechanical properties of nanostructures. The methodology is based on a two-step approach to compute the electronic density distribution in and around a nanostructure, and then the equilibrium configuration of its nuclei. The Electronic Problem embeds interpolation and coupled cross-domain optimization techniques through a process called electronic reconstruction. In the second stage of the solution, the Ionic Problem repositions the nuclei of the nanostructure given the electronic density in the domain. The new ionic configuration is the solution of a nonlinear system based on a first-order optimality condition when minimizing the total energy associated with the nanostructure. The overall goal is a substantial increase in the dimension of the nanostructures that can be simulated by using approaches that include accurate DFT computation. This increase stems from the fact that during the solution of the Electronic Problem expensive DFT calculations are limited to a small number of subdomains. For the Ionic Problem, computational gains result from approximating the position of the nuclei in terms of a reduced number of representative nuclei following the quasicontinuum paradigm.
Flow Induced Dynamics of a Pinned Droplet on the Surface of a Channel
Authors: Golpaygan Amirreza , Ashgriz Nasser
Published: April 2008

Dynamic behavior of a droplet adhering to the surface of a channel has been modeled under the influence of surrounding fluid. The numerical solution is based on solving Navier-Stokes equations for Newtonian liquids. The study includes the effect of interfacial forces with constant surface tension, also effect of adhesion between the wall and droplet accounted by implementing contact angle at the wall. The Volume-Of-Fluid method is used to numerically determine the deformation of free surface. Droplet deformation and final shapes have been predicted. A reduction in the surface tension allows the droplet to deform much easier. However, an increase in the fluid viscosity, although increases the shear force on the droplet, may not result in the deformation at high surface tension. It is shown that deformation of droplet significantly influences structure of channel flow. Effects of liquid droplet and channel fluid properties, namely density and viscosity, inlet velocity, surface tension and channel geometry on dynamics of the problem have been studied. Two different outcomes have been considered: the first one droplet with equilibrium shape and the other one when breakup of the droplet occurs. The border line between the disintegration region and equilibrium region is determined for different droplet surface tensions.
Transport Phenomena and the Associated Humping Formation in Laser Welding
Authors: Zhou J. , Tsai H. L. , Wang P. C.
Published: April 2008

Humping is a frequently observed welding defect in laser welding which is caused when the welding speed exceeds a certain limit while the other welding conditions remain unchanged. Humping is characterized by the appearance of unsmooth and discontinuity of humps at the surface of the weld. The formation of humping is generally understood to be caused by the complex heat transfer and melt flow in a high speed welding process. However, so far the fundamental mechanisms causing humping are not fully understood, and research on determining the onset of humping has been based on the “trial-and-error” procedure. In this paper, mathematical models previously developed by the authors for the transport phenomena in laser welding have been extended to investigate the formation of the humping defect. In this study, the transient heat transfer and melt flow in the weld pool during the keyhole formation and collapse, and melt solidification are calculated for a 3-D moving laser welding. Different humping patterns have been predicted by the present study in different laser power levels and welding speeds. From the present study, it was found that the formation of humping in laser welding is caused by the interplay between two important factors: a) the strong liquid metal flow in the real part of the keyhole induced mainly by the laser recoil pressure and b) the rapid solidification rate of the liquid metal. The humping pattern can be well explained by the calculated melt flow and the solidification process.
User-Centered Design of Course-Based Portfolios for Mechanical Engineering Student Learning
Authors: Guan Zhiwei , Yellin Jessica , Turns Jennifer , Kumar Vipin
Published: April 2008

One challenge for engineering educators is to design appropriate educational curricula that address both students’ needs and educators’ expectations. It is therefore important for the engineering education community to think about how to include students and faculty into the assignment design process. In this paper we discuss our use of user-centered design (UCD) principles, including early focus on users, empirical measurements, and iteration design, to design course-based portfolio (CBP) assignments for mechanical engineering students. To support the assignment design decisions, we collected early information about mechanical engineering students’ learning needs and educators’ expectations. Based on the design considerations that we identified for portfolio design, the CBP assignment is designed to ask students build a persuasive document and identify the connections between the course and mechanical engineering discipline. We measured our design by piloting the assignment with students and getting feedback from faculty in the Mechanical Engineering Department; this feedback reflects the effectiveness of the CBP and leads to design iterations and tradeoffs. We also identified several students’ learning opportunities and formed these opportunities into hypotheses to evaluate the impacts of course-based portfolios on students learning in the next formal study. This research demonstrates a successful practice of using user-centered design principles to design a course-based portfolio assignment for mechanical engineering students.
The Newmark Integration Method for Simulation of Multibody Systems: Analytical Considerations
Authors: Gavrea B. , Negrut D. , Potra F. A.
Published: April 2008

When simulating the behavior of a mechanical system, the time evolution of the generalized coordinates used to represent the configuration of the model is computed as the solution of a combined set of ordinary differential and algebraic equations (DAEs). There are several ways in which the numerical solution of the resulting index 3 DAE problem can be approached. The most well-known and time-honored algorithms are the direct discretization approach, and the state-space reduction approach, respectively. In the latter, the problem is reduced to a minimal set of potentially new generalized coordinates in which the problem assumes the form of a pure second order set of Ordinary Differential Equations (ODE). This approach is very accurate, but computationally intensive, especially when dealing with large mechanical systems that contain flexible parts, stiff components, and contact/impact. The direct discretization approach is less but nevertheless sufficiently accurate yet significantly faster, and it is the approach that is considered in this paper. In the context of direct discretization methods, approaches based on the Backward Differentiation Formulas (BDF) have been the traditional choice for more than 20 years. This paper proposes a new approach in which BDF methods are replaced by the Newmark formulas. Local convergence analysis is carried out for the proposed method, and step-size control, error estimation, and nonlinear system solution related issues are discussed in detail. A series of two simple models are used to validate the method. The global convergence analysis and a computational-efficiency comparison with the most widely used numerical integrator available in the MSC.ADAMS commercial simulation package are forthcoming. The new method has been implemented successfully for industrial strength Dynamic Analysis simulations in the 2005 version of the MSC.ADAMS software and used very effectively for the simulation of systems with more than 15,000 differential-algebraic equations.
Fuel Cell Integrated Energy System for Residential and Commercial Applications
Authors: Simon William E. , Chambers Terrence L. , Guillory John L. , Ventrapragada Varaprasad , Angelle Jeremy R. , Gulati Tanuj
Published: April 2008

Until recently the cost of fuel cells for terrestrial applications was prohibitive. Recently, several companies have begun developing high-performance, long-life and cost-effective fuel cell systems, and commercial units are now becoming available for stationary power generation. These systems can often be operated in conjunction with other energy systems to increase overall operational efficiency. A recent technology demonstration project at the University of Louisiana at Lafayette involved the installation, operation and analysis of a fuel cell and a desiccant dehumidification system, which is considered a good combination for the hot, humid climate of the U.S. Gulf coast. The three-year project involved technology assessment, hardware selection and procurement, installation, and operation of the two systems, followed by a performance analysis. The results were reported in a regional symposium. This paper describes the project, focusing on system operation and the results obtained, and predicts future possibilities for integrated energy systems of this type.
An Economic Analysis of Stationary Fuel Cell Power Plants
Authors: Pourmovahed Ahmad , Nejad Hamid
Published: April 2008

Fuel cells are often credited for being quieter, cleaner, more reliable and more efficient than traditional power plants. They may be used as the primary source of power or as a back-up system with significant benefits. They have potential for producing financial savings when used to produce electricity. The objective of this study was to determine the feasibility of using a 250-kW stationary fuel cell system as the primary provider of electrical power at an industrial facility. Additionally, the cost and payback period for such a system including hook up and maintenance were estimated. The biggest drawback to stationary fuel cells is the high initial cost. However, coupled with incentives such as rebates and cogeneration opportunities, select locations in the country may be suitable candidates for implementation. In addition, the type of application and power load cycle are key factors in selecting an appropriate fuel cell type. Most fuel cells favor operating continuously as they are not designed to withstand intermittently changing loads and their efficiencies and life time drop if they are cycled on and off. The only currently viable option is to select a facility located in a “fuel cell friendly” state with a minimum (base) electric demand of 250 kW, 24 hours a day, 5 days a week. The fuel cell would operate based on a “base load strategy”, providing electrical/thermal energy at a constant rate. A detailed economic analysis was carried out. It indicates that the payback period for a currently available large stationary fuel cell system installed in California is over 20 years in Los Angeles and about 15 years outside Los Angeles. This is primarily due to lower electric rates in Los Angeles. Despite multi-year programs providing various funding to assist this new technology, without significant cost reduction by fuel cell developers, no large-scale economic deployment of stationary fuel cells will be viable.
A Design Representation to Support the Automatic Dynamic Evaluation of Electromechanical Designs
Authors: Wu Zhaohong , Campbell Matthew I. , Fernandez Benito R.
Published: April 2008

This paper introduces research leading to a computer-aided design tool in which engineering designers can test various concepts in an environment equipped to automatically model the dynamics and then optimize the chosen components to best meet the specifications of the design problem. The input to the system is a graph of components where the components either include defined parameter values or are left as variables for the subsequent optimization. In this paper, “conceptual dynamics” is introduced with the goal of revealing the qualitative information of the system states, energy flow patterns, possible operation modes, degrees of freedom, etc. The dynamics of a system are captured in a multi-domain representation referred to as a conceptual dynamics graph (CD-Graph), which is composed of components and virtual couplers. The components feature both detailed multi-complexity models (bond graphs) and qualitative dynamics information (Conceptual Dynamics Matrices), and the virtual couplers include information on the interconnections of the eight domains (three translational, three rotational, electrical, and hydraulic). The Conceptual Dynamics Graph provides a platform for various design automation approaches and further dynamics performance optimization. This paper discusses an automatic approach that extracts the partial configuration of a complete design structure that contributes to the system dynamics. This allows designers to better understand the system and focus on the functional aspects that meet certain dynamic specifications. Finally an automatic model generation approach of CD-Graph is briefly illustrated.
Lifting Posture Analysis in Material Handling Using Virtual Humans
Authors: Kim Joo H. , Abdel-Malek Karim , Yang Jingzhou , Marler Timothy , Nebel Kyle
Published: April 2008

Adopting appropriate postures during manual material-handling tasks is the key to reducing human joint injuries. Although much experimentation has been conducted in an effort to model lifting, such an approach is not general enough to consider all potential scenarios in material handling. Thus, in this paper an optimization-based motion prediction method is used to simulate realistic lifting postures and predict joint torques to evaluate the risk level of injury. A kinematically realistic digital human model has been developed such that the complicated musculoskeletal human structure is modeled as a combination of serial chains using the generalized coordinates. Lagrange’s equations of motion and metabolic energy rate are derived for the digital human. The proposed method has been implemented to predict and evaluate the lifting postures based on the metabolic rate and joint torques. Our results show that different amount of external loads and tasks lead to different human postures and joint torque distribution, thus different risk level of injury.
Application of a PDMS Microsieve for the Patterning of Flagellar Motors in a Microfluidic System
Authors: Pooran Ryan , Tung Steve , Kim Jin Woo
Published: April 2008

We are in the process of developing hybrid micro devices that utilize the flagellar motors of Escherichia coli cells as actuators. For the micro devices it is important that the flagellar motors be tethered at specific locations on a given substrate in order to maximize its performance as actuators. In this paper we present results that demonstrate an effective method for patterning the flagellar motor actuators onto a substrate material. We also present the first experimental data which discusses the performance of the actuator in a microfluidic pump.
Important Parameters in Drop Coalescence at Planar Surfaces
Authors: Aryafar H. , Kavehpour H. P.
Published: April 2008

An experimental study has been performed to establish the principal elements that govern drop coalescence. The study consisted of placing drops of various sizes and physical properties on a planar interface. The coalescence process was recorded with the aid of a high speed digital camera. The experimental portion of the project was aimed at capturing the time of coalescence and the size of the secondary drop that formed after coalescence had finished. Results of the experiments, when scaled properly, showed clear patterns with respect to inertial and viscous terms. Dimensional analysis indicated that Ohnesorge number, Oh, had a strong influence on the behavior of drop coalescence. The ratio of secondary drop radius to primary drop radius, ri, was calculated to be approximately constant when Oh was much smaller than unity. However, as Oh approached unity from the lower bound, the value of ri decayed. No secondary drop was observed when Oh was greater than unity. Normalized coalescence times confirmed this trend by being properly scaled with inertial time scales for small Ohnesorge number and preferring viscous time scales when Ohnesorge number was greater than unity.
Light Transmission Characteristics of Thermochromic Liquid Crystals
Authors: Roth Timothy B. , Anderson Ann M.
Published: April 2008

This paper presents the results of a study to develop a novel thermochromic liquid crystal (TLC) temperature measurement system that uses light transmission instead of light reflection. We used Imagetherm 25C10W sprayable TLCs. The TLCs were painted on a clear surface and placed in a spectrometer. The amount of light transmitted at monochromatic wavelengths from 400 to 700 nm was measured for temperatures from 25–55 C under conditions of non-polarized, linearly polarized and cross polarized light. The transmission spectra exhibit a distinct “s-like” shape when the TLCs are in their active range. We detect significant changes in the transmission spectra for temperatures from 27 to 48 C (whereas in reflection the TLCs are useful over a significantly smaller range). We have analyzed the spectrometer data in a number of ways including (a) total amount of light transmitted (b) amount of red, green and blue light transmitted, and (c) spectral curve characteristics (peak transmission, inflection wavelength and wavelength for peak transmission) all as a function of temperature. There is a linear relationship between temperature and all of these variables which we believe can be exploited in the development of a CCD camera based light transmission system. We also investigated the effects of temperature overheat on the transmission spectra. Overheating the TLCs increases the amount of light transmission.
A Novel Approach to the Teaching of Thermodynamic Cycles and the Laws of Thermodynamics
Authors: Dartnall W. John , Reizes John
Published: April 2008

This paper outlines a simple particle mechanics model in which a single particle represents the thermodynamic fluid (gas) in a heat engine (exemplified by a piston engine). By mechanics based reasoning the model demonstrates the connection between the Carnot efficiency limitation of heat engines and the Kelvin-Planck statement of Second Law requiring only the truth of the Clausius statement.
Augmenting a Design Repository to Facilitate Product Family Planning
Authors: Fledderjohn Matthew , Shooter Steven B. , Stone Robert B.
Published: April 2008

A Design Repository has been created in an effort to archive existing products and the components in each product. With this function-based archiving system, designers can retrieve design information on existing products to assist in a new design project. The use of product families has emerged as an approach to exploit commonality for more efficient product development. However, the Design Repository does not contain explicit design information on platforms and modules. This paper describes information for the design of a platform and proposes a new data structure that organizes the information for augmenting the Design Repository. An information flow model for the development of a single product is modified to describe the flow of information needed for product platform design. The information flow model and associated data structure has been shown to be effective in representing three common product families: the Black & Decker Firestorm tool set, Kodak single-use cameras, and the IceDozer family of ice scrapers. With this data structure implemented into the existing repository, designers can find useful information on how to create different products based on the a common platform.
Development of a New Design Hydraulic Engine Mount
Authors: Nakhaie Jazar G. , Christopherson J.
Published: April 2008

In this paper a new design of the passive hydraulic engine mount is introduced. A means for improved decoupler control is introduced that does not noticeably affect the mechanisms steady state behavior, but improves start up and transient response. In addition, the decoupler mechanism is incorporated into a smaller, lighter, yet more tunable and hence more effective hydraulic mount design. The performance of the new hydraulic mount is discussed by means of a full nonlinear model. The increased design flexibility afforded by the redesigned support structure provides means by which to tune the engine mount to various engine support configurations. In addition, the proposed mount does not rely as heavily on hysteretic damping provided through elastomeric materials, which can be difficult to control, but more so on fluid behavior inside the engine mount; therefore, the damping of the system is much more tunable than previous hydraulic engine mount designs.
A Desktop Networked Haptic VR Interface for Mechanical Assembly
Authors: Seth Abhishek , Su Hai-Jun , Vance Judy M.
Published: April 2008

This paper presents the development of a PC-based 3D human computer interface for virtual assembly applications. This system is capable of importing complex CAD (Computer Aided Design) models, rendering them in stereo, and implementing haptic force feedback for realistic part interaction in virtual environments. Such an application will facilitate wider acceptance of the use of a VR interface for prototyping assembly tasks. This interface provides both visual and haptic feedback to the user, while allowing assembly tasks to be performed on a desktop virtual environment. The network module has the ability to communicate with multiple VR systems (such as CAVE etc.) at geographically dispersed locations using a non-dedicated network channel. The potential benefits of such a system include identification of assembly issues early in the design process where changes can be made easily, resulting in a more efficient and less costly product design process.
Computer-Integrated Design and Manufacturing of Packaging Machines
Authors: Buske Scott E. , Liu Tien-I
Published: April 2008

Automated packaging machines must be constantly redesigned to accommodate ever changing packing. There is little time to make these changes and no room for error. In this work, computer-integrated design and manufacture of a packaging machine has been conducted. A knowledge base system has been developed, which checks for errors in user input, updates all assemblies per the user input, checks for part interferences in the assembly, holds the new design to accepted design standards, and sends warning messages to the user’s computer screen in the event of a problem. The knowledge base then creates new intelligent part numbers. These part numbers provide the informational link from Engineering to Production as they contain all the new part information needed to make the parts. These part numbers are entered into a program that automatically creates the new tool paths for the CNC mill. The entered part number is automatically milled into the part to insure the correct part was entered. The cost of design and manufacture is then reduced substantially. This knowledge base also extends into sales for quoting and for new job creation which expedites the entire process.
A Microfluidic Filter Chip for Highly Sensitive Chemiluminescence Detection of E. Coli O157:H7
Authors: Srinivasan Balaji , Varshney Madhukar , Tung Steve , Li Yanbin
Published: April 2008

This paper describes a rapid and highly sensitive chemiluminescence detection scheme for E. coli O157:H7 bacteria by using a microfluidic filter chip. The stepped configuration design of the filter chip enables the formation of a monolayer of beads-bacteria-peroxidase labeled antibodies sandwich complex inside the microchamber. The addition of Luminol to the sandwich complex produces a chemiluminescence signal proportional to the concentration of E. coli. The chemiluminescence signal is captured by a fiber optic light guide connected to a luminometer. The monolayer maximizes the optical accessibility of the E. coli cells to the detecting light guide and high chemiluminescence signal strength is achieved. A multi-sampling technique is used to enhance the E. coli capture efficiency by 180%. Due to the combination of the filter chip and the sampling technique, no enrichment scheme is used for detecting extremely low cell concentrations, which is difficult to accomplish with other rapid detection methods.
The Effect of Fin Geometry on Design of Compact Off-Set Strip Fin High Temperature Heat Exchanger
Authors: Subramanian Sundaresan , Ponyavin Valery , De Losier Clayton Ray , Chen Yitung , Hechanova E. , Peterson Per F.
Published: April 2008

This paper deals with the development of a three-dimensional numerical model to predict the overall performance of an advanced high temperature heat exchanger design, up to 1000°C, for the production of hydrogen by the sulfur iodine thermo-chemical cycle used in advanced nuclear reactor concepts. The design is an offset strip-fin, hybrid plate compact heat exchanger made from a liquid silicon impregnated carbon composite material. The two working fluids are helium gas and molten salt (Flinak). The offset strip-fin is chosen as a method of heat transfer enhancement due to the boundary layer restart mechanism between the fins that has a direct effect on heat transfer enhancement. The effects of the fin geometry on the flow field and heat transfer are studied in three-dimensions using Computational Fluid Dynamics (CFD) techniques. The pre-processor GAMBIT is used to create a computational mesh, and the CFD software package FLUENT that is based on the finite volume method is used to produce the numerical results. Fin dimensions need to be chosen that optimize heat transfer and minimize pressure drop. Comparison of the overall performance between two fin shapes (rectangular versus curved edges) is performed using computational fluid dynamics techniques. Fin and channel dimensions need to be chosen such as to optimize heat transfer performance and minimize pressure drop. The study is conducted with helium gas and liquid salt as the working fluids with a variety of Reynolds number values and fin dimensions. Both laminar and turbulent modeling is performed for the helium side fluid flow. The effect of the fin geometry is performed computational fluid dynamics techniques and optimization studies are performed. The model developed in this paper is used to investigate the heat exchanger design parameters in order to find an optimal design.
The Effect of Atomization Method on the Morphology of Spray Dried Particles
Authors: Eslamian Morteza , Ashgriz Nasser
Published: April 2008

Effect of various atomization methods as well as solution concentration on the morphology of MgSO4 particles produced by spray drying of aqueous solutions of MgSO4 is investigated. Four types of atomizers are tested: (1) A mesh vibrating nebulizer, which generates low velocity droplets of 0.2 m/s with a size range of 1μm to 7 μm. (2) A splash plate nozzle, which generates droplets with an average velocity of 21 m/s and a size range of 40 μm to 500 μm. (3) An air mist atomizer, which generates droplets with an average velocity of 22 m/s and a size range of 20 μm to 150 μm. (4) A pressure atomizer, which generates droplets with an average velocity of 20 m/s and a size range of 30 μm to 1000 μm. Several types of particle morphologies are identified in this research. For the vibrating mesh nebulizer most of the particles are non-disrupted thick wall shells. For the splash plate and the air mist atomizer most of the particles are deformed spherical shells due to contraction and some are uniformly or non-uniformly disrupted. Higher initial solute concentration thickens the shell wall and prevents the particles to burst. It is found to be hard to obtain fully filled particles even for nearly saturated solutions at room temperature.
Validation of Longitudinal Vehicle Estimation Techniques on a Heavy Truck Test-Bed
Authors: Heffernan Matthew E. , Bevly David
Published: April 2008

Commercial vehicles display a large variation in their parameters, and due to many current trends in vehicle control systems, identifying these parameters has been the subject of much research. Using the National Center for Asphalt Technology’s test track and instrumented Freightliner vehicles as a test bed, this paper sets out to provide analysis of real world and simulated estimation results and explore how sensor accuracies can degrade these results. Various vehicle parameters are identified using both the existing test conditions of the facility and simulated data. The estimation accuracy and performance are then analyzed for validation and use in other vehicle design arenas.
Force Prediction in Milling of Carbon Fiber Reinforced Polymers
Authors: Sheikh-Ahmad Jamal , Yadav Rahul
Published: April 2008

Fiber reinforced polymers are widely used in the transportation, aerospace and chemical industries. In rare instances these materials are produced net-shape, and secondary processing such as machining and assembly may be required to produce a finished product. Because fiber reinforced polymers are heterogeneous materials, they do not machine in a similar way to metals. Thus, the theory of metal machining is not valid for the analysis of machining of fiber reinforced composites. Previous attempts in modeling this problem have adopted Merchant’s theory for metal cutting by assuming that chip formation takes place in a shear plane where the inclination angle is determined by the minimum energy principle. This class of models showed that model predictions are valid only for fiber orientations less than 60°. Furthermore, these models are incapable of predicting cutting forces for multidirectional laminates or complex tool geometry. The work presented here focuses on providing a predictive model for the cutting forces in milling both unidirectional and multidirectional laminates. The model is based on the specific cutting energy principle and accounts for a wide range of fiber orientations and chip thickness. Results from this model were found to be in good agreement with experimental results over the entire range of fiber orientations from 0 to 180°.
Thermal Conductivity Measurements of Nylon 11-Carbon Nanofiber Nanocomposites
Authors: Cummings Antonette T. , Shi Li , Koo Joseph H.
Published: April 2008

Nylon 11, a popular material for commercial use, has been combined with low-percent loads of carbon nanofibers (CNFs) to tailor mechanical, fire retardancy, and thermal properties. Transmission electron microscopy images show that the CNFs are randomly aligned in the polymer matrix. We show that the thermal conductivity is minimized at a certain percent loading of CNFs due to a large thermal contact resistance between the CNFs and the medium.
Buckling Instabilities in Coupled Nanoscale Structures
Authors: Wilber J. Patrick , Clemons Curtis B. , Pudloski Amy E. , Young Gerald W. , Buldum Alper , Quinn D. Dane
Published: April 2008

We consider the bending of two nanotubes coupled together with van der Waal forces acting transverse to the axis, and subject to axial loads. The nanotubes are modeled as elastica while the interaction forces are derived from a Lennard-Jones 12-6 potential. The elastica are assumed to be a fixed distance apart at their ends, not necessarily equal to the equilibrium distance as identified from the Lennard-Jones potential. Therefore, the equilibrium configuration is not necessarily straight. As the compressive axial force increases, the beams can undergo buckling instability and the critical load depends not only on the material properties of the structure, but the geometry of the system as well. The continuum model is subjected to a Galerkin reduction to develop a reduced set of equations that can be used to calculate the equilibrium configuration of the system as well as the stability of these configurations. We show that the buckling instability in this model is significantly affected by the presence of the interaction force as well as the separation of the nanotubes at their ends.
Use of Interactive Computer Software in Teaching Thermodynamics Fundamental Concepts
Authors: Karimi Amir
Published: April 2008

In recent years many publishing companies have provided optional computer software for engineering textbooks. Some of these software packages are tools for enhancing classroom instruction and others are capable of engineering analysis. Several software are currently available as an option with most engineering thermodynamics. They can be used for thermodynamic property evaluations and are extremely useful tools in analysis and design in introductory courses. They are also useful in teaching fundamental thermodynamic concepts. The most significant advantage of these software programs is that no prior knowledge of programming language is necessary in their applications. This paper will discuss the benefits associated with the use of computer software in introductory thermodynamics courses. Available software tools are compared and, in each case, their strengths and limitations are highlighted. The paper describes how one software tool has been integrated into our introductory thermodynamics course to teach the fundamental concepts. Several examples are provided.
Effect of Sub-Micron Thin Film on Surface Temperature During Chemical Vapor Deposition
Authors: Huang Wei , Tian Weixue , Chiu Wilson K. S.
Published: April 2008

In this paper, we investigated the effect of the film thickness on heat transfer and subsequent film temperature distribution of an optical fiber as it traverses through a chemical vapor deposition (CVD) reactor. A 50 nm thick carbon coating is applied on the optical fiber as it moves through the CVD reactor. In this process, the only heat source is the hot optical fiber entering the CVD reactor from the draw furnace. Radiation heat transfer from the optical fiber as it is being coated plays an important role during CVD carbon film growth. The carbon film will change the effective emissivity of the optical fiber as it traverses through the CVD reactor. This study will calculate the effective emissivity of this film-fiber structure based on wave theory, and evaluate the optical fiber’s resulting temperature field and rate of heat transfer loss during chemical vapor deposition. Results are correlated to operating conditions.