bluuebunny/crossref_metadata_2025 huggingface dataset:
A Method for the Rapid Characterization of Combustion Properties of Liquid Fuels Using a Tubular Burner
Authors: Love N. D. , Parthasarathy R. N. , Gollahalli S. R.
Published: May 2009

Knowledge of the combustion and pollutant emission characteristics is important in the application of both existing and newly developed fuels. A technique for the rapid characterization of flame radiation properties and emission characteristics of liquid fuels was developed for this purpose. Liquid fuel was injected into a heated air stream at known rates with a syringe pump; the feed line was heated (temperature of 425°C) to pre-vaporize the fuel before burning, to avoid the effects of evaporation parameters on measurements. Temperatures of the fuel and air were monitored using K-type thermocouples embedded within the feed lines. A laminar methane-air flame was issued from a stainless steel tubular burner (9.5mm inner diameter) and used as the ignition source. The methane supply was shut off after the onset of the burning of the vaporized liquid fuel, in order to eliminate the effects of burning methane in the measurements. Several liquid fuels were tested, including commercially available petroleum-based No. 2 diesel fuel, canola methyl ester (CME B 100) biodiesel, kerosene, methanol, toluene, and selected alkanes. A steady burning flame was achieved for all fuels. Radiative heat flux measurements were made with a high-sensitivity pyrheliometer and the radiant fraction of heat release calculated. The radiant heat fraction served as an indication of sooting tendency of the fuels. NO, CO, and CO2 emission measurements were also made. The measurements demonstrate the feasibility of the current technique for the rapid characterization of combustion properties of liquid fuels, utilizing small fuel quantities.
A Preliminary PIV and Analytical Investigation of Wall Shear in Micro Channel Slug Flow
Authors: Black Kelly , Bruno Bradford A. , Martel Joseph
Published: May 2009

This paper describes the methods and initial results of an investigation aimed at answering questions of engineering significance pertaining to slug flow. The authors use two approaches to study slug flow. First, the analytical solution of Gaskell et al and Gurcan [5,6] is examined in detail, with special attention being paid to its predictions pertaining to the special case of slug flow. The numerical behavior of this solution and the measures needed to enhance its convergence are also commented upon. Second, micro-PIV data of water/oil slug flow in a micro-channel is reported and examined in light of the predictions of the Gaskell model. Quantitative results showing the details of the re-circulating internal flow fields in the slugs are presented. Results for wall shear stress distributions and evolution of the velocity profiles from the centerline to the rear interface are also presented. Significant increases in the wall shear stress (compared to a fully developed Poiseuille flow) are observed in the regions near the fluid interfaces.
A Numerical Study of the Onset of Cellular Benard Convection in Shear Rate Dependent Non Newtonian Fluids in Porous Media: Non-Darcian Effects
Authors: Murty V. Dakshina , Pratt David M. , Byrd Larry W.
Published: May 2009

A numerical method based on the finite element method is applied to the study of onset of Benard convection in porous media. The flow is described using the so-called Darcy Brinkman model, which has close resemblance to the Navier-Stokes equations. Itis found that for Darcy numbers less than 0.0001 the results are indistinguishable from regular Darcy flows. The non-Newtonain nature of the fluid is described by the so-called power law model, of which Newtonian fluid is a special case. Numerical results are presented for n varying from 0.4 to 1.5. The critical value of Rayleigh number for onset of convection for Newtonian fluids is found to be 40 which is close to the theoretical value of 4π2; boundary conditions on the horizontal walls have little effect in the sense that whether it is a slip or free (no shear condition) the results appear to be the same for onset of cellular motion. It is also found that the value of critical Rayleigh number increases with power law index.
Error Propagation in Heat Release Analysis of Pilot Ignited Natural Gas Combustion
Authors: Weathers J. B. , Marvel B. T. , Srinivasan K. K. , Mago P. J. , Chamra L. M. , Steele W. G.
Published: May 2009

Uncertainty within measured variables and how such errors propagate throughout a given equation or set of equations can greatly affect the accuracy and understanding of the result for a given experiment. The major motivation (or impetus) for performing a detailed uncertainty analysis before beginning an experiment is to identify variables or parameters that would have the greatest/least impact on the total uncertainty of the result. The scope of this study is to perform a detailed uncertainty analysis on estimates of net heat release in a compression ignition engine. The analysis will examine each term of the net heat release rate equation, which is routinely estimated using a single zone thermodynamic model, and evaluate the respective Uncertainty Magnification Factors (UMF) and Uncertainty Percentage Distribution (UPC). Since the net work output from the engine is directly related to in-cylinder pressure data, it is important to evaluate the uncertainties associated with cylinder pressure measurement. The primary objective of this paper is to analyze the effect of biased and precision uncertainties associated with the measured cylinder pressure data on the rate of heat release (ROHR) of a pilot ignited natural gas engine. Sensitivity analysis of other parameters such as the correct estimation of compression ratio and using appropriate thermodynamic properties of combustion gases are also discussed. The estimates from this analysis are expected to aid the development of a detailed experimental matrix to analyze the nature of energy release and performance of combustion engines.
Research Integrated Into Core Courses of an Undergraduate Program
Authors: Nowak Michael D.
Published: May 2009

Each year of the Biomedical Engineering program at the University of Harford includes courses that include student based research projects. The Freshman course “Introduction to Engineering” course includes projects requiring the designing, building and testing of devices (including statistical analysis and in-class presentations). During the Sophomore year, “Biomedical Materials” includes multiple journal-style laboratory reports. During the Junior year, “Biomechanics” includes student research projects (including such issues as reproducibility and accounting for human variances), and “Biofluids” includes a research paper. The senior year course, “Bioinstrumentation”, includes projects monitoring physiological parameters. The senior year also includes two sets of research and design-based courses: two courses in senior design pursuing research for outside principals, and an off-campus research course where the student performs as the engineer on a research project. The former course culminates in a formal oral and written presentation. The latter course allows students to work at local, regional, and national medical facilities, and to participate in clinically useful research. Our philosophy for these courses has been both to involve the student in the requirements and needs of pursuing research, and to prepare them for the expectations of those who will be reviewing their efforts after they graduate.
Simulation of a Rectangular Cylinder in Cross Flow in a Microchannel Using Information Preservation (IP) Method
Authors: Kursun U. , Kapat J. S.
Published: May 2009

A numerical simulation is performed to study the characteristics of the gas flow over a constant temperature rectangular cylinder in a cross flow in a micro channel. The non-isothermal Information Preservation (IP) method is employed to eliminate the statistical scatter of Direct Simulation Monte Carlo (DSMC) at low Reynolds numbers. Pressure boundary conditions based on the characteristic theory are implemented in the algorithm. The simulation results are compared with the references available in the literature. This study will form a base for our future particle-atomistic hybrid computations.
Effect of Insertion of a Heat Flux Gage Into a High Temperature Cylindrical Blackbody Cavity on the Gage
Authors: Abdelmessih Amanie N. , Horn Thomas J.
Published: May 2009

Detailed transient thermal models have been developed to simulate a heat flux gage calibration process capable of generating high heat flux levels. These heat flux levels are of interest to the reciprocating and gas turbine engine industries as well as the aerospace industry. The transient models are based on existing, experimentally validated steady state models of a cylindrical blackbody calibration system. The steady state models were modified to include insertion of a heat flux gage into the hot zone of the calibration system, time-varying electrical current that passes through the resistance heated blackbody, and the resulting heating of the heat flux gage. Heat fluxes computed using detailed transient models were compared to experimental measurements. The calculated and measured transient heat fluxes agreed to within 2 percent, indicating that the models had captured the physical phenomena in the transient calibration. The predicted and measured transient heat fluxes were also compared for two different blackbody configurations. The effect of convection on the blackbody extension was evaluated and found to be a minor factor.
Transient Response of Beams, Plates, and Shells to Impulsive Loads
Authors: Abrate Serge
Published: May 2009

Beams, plates and shells are used in many applications where there can be subjected to short duration loads due to impacts or pressure blasts. Here the response of such distributed systems is examined using the modal expansion technique for pulse shapes typically observed during impacts and explosions. The objective is to gain an understanding of the behavior of these structures. For beams and plates the natural frequencies are generally well separated and, typically, a small number of modes participate in the response. Pulses can be classified as being either short, long, or intermediate in comparison with the period of the fundamental vibration mode. Very different behaviors are observed for the three types of pulses. For short pulses, the response depends on impulse applied not on the shape of the pulse and it can be accurately predicted by the response to an equivalent impulse. For long pulses, the maximum response depends on the magnitude of the load applied. For shells, the effect of curvature can be significant and result in several modes with close frequencies. In that case the response is more complicated since many modes participate in the response. In this work, the criteria are developed for predicting the response of each mode to a various pulses and determine how many modes participate in the response. The results obtained are applicable with any other analysis method including the finite element method.
Analytic Model of a Crash Energy Absorption Structure for Crashworthy Design of an Inflatable Morphing Body
Authors: Lee Dong Wook , Ma Zheng-Dong , Kikuchi Noboru
Published: May 2009

The authors have studied a crash energy absorbing (CEA) truss structure with a locking mechanism to provide rigidity and energy absorption capability during a vehicular. In this paper, we focus on the analytic model of the CEA structure. An analytical model for the CEA truss structure design will be developed. The proposed CEA structure is composed of a morphing truss structure with movable thin-walled members for morphing purposes, members which will be locked in designated positions either before or during the crash. We will describe how to model the CEA structure analytically based on the energy absorbed by the CEA structure.
Design Collaboration Between High School, On-Campus, and Distance Engineering Students
Authors: Cavalli Matthew , Carlson Nate , Compton Pat
Published: May 2009

A collaborative design project has been implemented in a junior-level materials selection and manufacturing course. The team-based design problem involved the design of playground equipment for elementary school children. Focus groups of elementary students and a review of applicable construction standards were used to set design requirements. Each team comprised undergraduate on-campus students, undergraduate distance education students and junior/senior high school technology students. Initial design choices were made by the entire group. Subsequent calculations of stress, deformations, etc. to refine the design as well as choices of materials and manufacturing processes were primarily the purview of the undergraduate students. Drafting and integration of the design segments into a complete computer model was the responsibility of the high school students. Continuous communication between the groups was required for the process to be successful. This collaboration was facilitated via online forums and site visits. An overview of the project structure is presented along with a summary of the project outcomes and recommendations for improving the process.
Experimental Study of Concentration Polarization at a Microchannel-Nanochannel Interface
Authors: Zangle Thomas A. , Mani Ali , Santiago Juan G.
Published: May 2009

Recent advances in fabrication methods allow us to study and leverage the unique flow regimes offered by nano-scale fluidic channels, [1–3] and recent work suggests that the physics of microchannel/nanochannel interfaces present opportunities for novel methods of sample preconcentration and analysis. [4–6] In nanochannels, channel height is of the same order of the electric double layer (EDL) thickness, leading to a decreased electrical resistance relative to the fluidic resistance of the channel. More importantly, analyte molecules undergoing electrophoresis spend a significant amount of time within EDLs. This has a profound effect on the interfaces between micro- and nanochannels. In particular, for negatively charged walls and a nanochannel in series with two microchannels, the concentration of ions (of both signs) increases on the cathodic side of the nanochannel and decreases on the anodic side. This phenomenon is called concentration polarization (CP) or the exclusion enrichment effect. [4, 5] There is a dearth of basic studies of these phenomena and the coupling of electroosmotic flow with concentration polarization. We present experimental validation of a computational model which predicts the development of concentration polarization. Furthermore, we will show preliminary results demonstrating focusing and separation of analyte anions in the cathodic side microchannel. This focusing is due to a balance of advection and electrophoretic migration. Anionic analytes focus and separate according to electrophoretic mobility.
Optimization Based Approach to Automate Fatigue Durability Test Load Development
Authors: Muthu Jaychandar , Choi Brian
Published: May 2009

Loads for structural fatigue durability tests are often developed by considering only the load data and ignoring the structure and its failure modes. Typically, in these procedures, the load data is directly used with a fatigue damage calculation method to compute the most damaging loading direction and magnitude. These processes ignore the underlying structure and hence may not arrive at loading modes that are sensitive to the failure modes of the structure. The structure, with its failure modes, wield considerable influence on the test load selection and ought to be considered in the test development. FEA tools can be employed for this purpose. However, due to the iterative nature of the test development process and the repeated FEA analysis it entails, the development task can become tedious. Here, an optimization based approach to automate the test load development process is proposed. This methodology leverages optimization algorithms to arrive at the test load cycles with proper load phasing even when a large number of load channels are involved. This method permits linear or nonlinear FEA procedures with component or system level test setups. This method also allows for maximizing the fatigue damage at the primary ‘key life’ failure location. A range of loading constraints — from constraints based on durability loading histories to constraints due to testing rig limitations — may be applied. In this discussion, a unique approach to setup lab test development problems that are conducive to optimization algorithms is delineated. As a part of this process, a novel approach to set loading constraints by utilizing multidimensional scatter plots of the existing loading histories will also be shown. The effectiveness of well known optimization methods in searching and arriving at the test load cycles will be also highlighted.
Three-Dimensional Fluid Flow and Coupled Heat Transfer in Simplified Bipolar Plates
Authors: Wu Jianfei , Nie Jianhu , Chen Yitung
Published: May 2009

Numerical simulations were performed for three-dimensional fluid flow and coupled heat transfer in simplified bipolar plates. The Reynolds number of inlet flow is varied from 100 to 900 on the anode side while the Reynolds number is maintained as a constant of 100 on the cathode side. The solid wall surfaces of the bipolar plates are assumed to be adiabatically insulated, except that the active areas of the channels are supplied with uniform heat flux. Results of velocity and temperature distributions for different Reynolds numbers are presented and discussed. It is shown that effects of flow pattern on temperature distributions in channels becomes negligible when the Reynolds number is as high as 900.
Application of a Modified Quality Function Deployment Method for MEMS
Authors: Lamers Tina L. , David Milnes , Goodson Ken , Ishii Kos , Pruitt Beth L.
Published: May 2009

Quality Function Deployment (QFD) has long been used as a successful design methodology in the heavy industrial and automotive industries. QFD helps designers utilize the ‘voice of the customer’, or customer requirements, to determine which engineering metrics or product specifications are the most essential [1]. This prioritization helps designers know what part of the product or process is most beneficial to focus on during design, resulting in products that better meet customer requirements and generate increased commercial success. QFD and most other design methodologies have rarely been applied to MEMS products [2]. In the case of QFD, the structure of the most common format of the tool dictates that engineering metrics should be related to parts characteristics in the second step of applying QFD. This causes difficulties in using the tool for MEMS as most MEMS do not have physical ‘parts’ that are assembled into a final device. Rather, MEMS have product specifications and a manufacturing process used to create the product. Generally there is a tight link between product and process in MEMS. This link has been utilized in creating a modified version of QFD that relates engineering metrics to design concepts, including product conceptualization and manufacturing process. The modified QFD utilizes aspects of Pugh Concept Selection, and differs from typical QFD primarily in consideration of product idea and manufacturing process in the early phases of product definition. The modified QFD was applied to a MEMS project whose goal was to develop a handheld device that allows users to control the selection and release of a variety of stored scents. The technique was also applied to a microscale heat exchanger for integrated circuits. The scent dispenser and heat exchanger were designed and prototyped at Stanford University in 2005 and 2006, respectively. The modified version of QFD gave insight early in the product definition phase on which design concept to pursue to prototype. Use of this and other design methodologies in the MEMS field could shorten the time it takes to progress through product development to volume manufacturing, and increase confidence in the marketability of the chosen design and manufacturing process. A case study demonstrating the effects of using modified QFD Phase II to assist in finding a good fit between technical capabilities and market application was performed by the author on an acoustic sensor technology [3].
Effect of Bone Tumor and Osteoporosis on Mechanical Properties of Bone and Bone Tissue Properties: A Finite Element Study
Authors: Gohil Vipul P. , Canavan Paul K. , Nayeb-Hashemi Hamid
Published: May 2009

This research is aimed to study the variations in the biomechanical behavior of bone and bone tissues with osteoporosis and bone tumors. Osteoporosis and bone tumors reduce the mechanical strength of bone, which creates a greater risk of fracture. In the United States alone, ten million individuals, eight million of whom are women, are estimated to already have osteoporosis, and almost 34 million more are estimated to have low bone mass (osteopenia) placing them at increased risk for osteoporosis. World Health Organization defines osteopenia, as a bone density between one and two and a half standard deviations (SD) below the bone density of a normal young adult. (Osteoporosis is defined as 2.5 SD or more below that reference point.). Together, osteoporosis and osteopenia are expected to affect an estimated 52 million women and men age 50 and older by 2010, and 61 million by 2020. The current medical cost of osteoporosis total is nearly about $18 billion in the U.S. each year. There is a dearth of literature that addresses the effects of osteoporosis on bone tissue properties. Furthermore, there are few studies published related to the effect of bone tumors such as Adamantinoma of long bones, Aneurysmal bone cyst, Hemangioma and others on overall behavior of bone. To understand the variations in bio-mechanical properties of internal tissues of bone with osteoporosis and bone tumor, a 2D finite element (FE) model of bone is developed using ANSYS 9.0 ® (ANSYS Inc., Canonsburg, PA). Trabecular bone is modeled using hexagonal and voronoi cellular structure. This finite element model is subjected to change in BVF (bone volume fraction) and bone architecture caused by osteoporosis. The bone tumor is modeled as finer multi-cellular structure and the effects of its size, location, and property variation of tumor on overall bone behavior are studied. Results from this analysis and comparative data are used to determine behavior of bone and its tissue over different stage of osteoporosis and bone tumor. Results indicate that both bone tumor and osteoporosis significantly change the mechanical properties of the bone. The results show that osteoporosis increases the bone tissue stiffness significantly as BVF reduces. Bone tissue stiffness is found to increase by 80 percent with nearly 55 percent reduction of BVF. The results and methods developed in this research can be implemented to monitor variation in bio-mechanical properties of bone up to tissue level during medication or to determine type and time for need of external support such as bracing.
Development of Finite Element Analysis Lab Module in the Second Course of Solid Mechanics
Authors: Chaphalkar Pramod , Maletta Mike
Published: May 2009

Many universities have started introducing Finite Element Analysis (FEA) at an earlier point in the curriculum. However, there is a wide diversity of university backgrounds, course content and sequence, pedagogical objectives and approaches, etc. This paper describes the development of FEA lab modules in the second course of solid mechanics in our specific context. Students in this course were introduced to FEA earlier in the first course of statics and solid mechanics. They had learned the basic steps in FEA for axially loaded and planar truss structures. In the second course, the FEA was extended to the planar cases. One of the objectives was to make the students aware of the descretization and numerical errors of the FEA. Hence there was a particular focus on element displacement fields and how they influence element behavior in comparison with an actual structure behavior. The lab modules were designed to be complementary to the class room learning. Approximate nature of the FEA was taught via the lab modules on descretization errors and numerical errors. The descretization error was demonstrated in the first part of the lab wherein different types of elements for planar problems were compared. One cantilever beam problem was solved with different types of elements and the results were compared with the theoretical value. Numerical error was studied in the second part of the lab wherein the effect of the element shape quality on the results was studied. A systematic study of the effect of mesh distortion was undertaken. ANSYS Parametric Design Language (APDL) macros were developed to change the mesh distortion quickly in a controlled fashion. A study of convergence of the results followed in the third part of the lab. A reasonable convergence was obtained for a plate with a central hole for which the theoretical results are known. Once the students grasped the need of convergence, a real life problem was attempted in the fourth part of the lab. The actual results are not known in the real life and a reasonable convergence needs to be established for acceptable results and for subsequent analysis and design. Design of a seat belt buckle was undertaken. A Pro/E CAD model was imported into ANSYS. The students used the subset of the CAD model to build their FE model considering only the relevant part, the symmetry and the mid plane. At the end of the semester, the students used the FEA tools for a real life design problem with a firm grasp of the approximate nature of the method.
Design of a Robust, Multifunctional Thermal Protection System Incorporating Zero Expansion Lattices
Authors: Steeves Craig A. , He Ming , Maxwell Peter T. , Evans Anthony G.
Published: May 2009

On hypersonic vehicles flying within the atmosphere, viscous drag on acreage surfaces, even far from the hot leading edges, generates high temperatures, and, consequently, high thermal stresses and strains. This leads to two significant problems in the design of hypersonic airbreathers: insulation of the cool internal volume of the vehicle from the inclement exterior conditions, and reducing geometric changes in the vehicle surface to preserve aerodynamic shapes and to make it possible to connect the aeroshell to the cool structure within. A multifunctional sandwich structure incorporating very low density insulation as the core, with the structural stiffness provided by a hot face consisting of a low (or zero) thermal expansion lattice, fulfills these requirements. Here we analyze the feasibility of such a structure and discuss design and manufacturing issues, concentrating particularly on bonded joints in the lattice and connections between the hot face and the cool internal structure.
On Line-Affective State Monitoring Device Design
Authors: Lanz Anja , Croft Elizabeth
Published: May 2009

The monitoring of human affective state is a key part of developing responsive and naturally behaving human-robot interaction systems. However, evaluation and calibration of physiologically monitored affective state data is typically done using offline questionnaires and user reports. This paper investigates the potential to use an on-line device to collect user self reports that can be then used to calibrate physiologically generated affective state data. The collection of on-line calibration data is particularly germane to human-robot interaction where the physiological responses of interest include those related to more high frequency affective state events related to arousal (surprise, fear, alarm) as well as the more low frequency events (contentment, boredom, pleasure). In this context, this paper describes the development of an experimental device, and a preliminary study, to answer the question: Can people report, on-line, two degree of freedom continuous affective states using a hand held device suitable for calibration of physiologically obtained signals? In the following paper, we report on both the device design and user trials. Further work, using the device to calibrate existing models of the user’s affective state during human-robot interaction, is ongoing and will be reported at the time of the conference.
Multiphysics, Multiphase Modeling of Carbon Nanotube Synthesis Process by Chemical Vapor Deposition
Authors: Hosseini Mahmoud Reza , Jalili Nader
Published: May 2009

In the present paper, a comprehensive modeling framework is proposed to conduct multiphysics, multiphase modeling of carbon nanotube (CNT) fabrication process by chemical vapor deposition (CVD). The modeling is based on fluid dynamics, heat transfer, chemical reaction, as well as mass transport phenomena which have been fully coupled with each other. The inserted gasses are considered as methane (CH4) as the main hydrocarbon gas and hydrogen (H2) as the process enhancement gas. In the gas phase reaction section, a novel set of reactions for CH4 hydrocarbon gas is proposed which is based on 71 different chemical reactions that take place near CVD inlet. Also, surface reactions are modeled by considering 19 set of reactions acting near substrate surface which lead to CNTs formation. The investigation is performed for different combination of gas flow rate quantities ranging from 500 to 1000 sccm (standard cubic centimeter per minute) for methane and 250 to 500 sccm for hydrogen gas. Also, the quartz tube temperature is considered to change from 700 to 1000 °C. Since the thermal specifications for each species are calculated individually, the gas flow inside the quartz tube is treated as nonisothermal flow. Numerous simulations are conducted and the results are compared with the fabricated CNT’s images taken by the SEM (scanning electron microscopy). Utilizing the obtained diagrams from modeling, the effects caused by gas mixture flow rate and temperature changes on the production rate of gas phase species such as H, CH3, C2H2 and bulk carbon species (C and 2C) that produced by surface species TC and TC2 are investigated. It is found that increasing the fabricated temperature causes a rise in species production rate. However, it is observed that the produced species respond differently to any change in hydrogen and hydrocarbon flow rates. The velocity, temperature profile as well as concentration distribution along the silicon substrate length have been also investigated. This study can lead to a controlled CNTs manufacturing process when combined with in-situ measurement systems.
An Analytical Modeling Framework for Piezoelectric-Based Microcantilever Actuator/Sensor With Thermal Effects Consideration
Authors: Salehi-Khojin Amin , Jalili Nader
Published: May 2009

In many surface science applications, piezoelctrically-actuated based micro-machines offer outstanding opportunity to detect topography of substrate in the scale of nano-meter. As the tip scan the surface of the sample, the laser beam deflected from the end of cantilever provide information related to nanoscale surface texture. However, application of laser beam to detect deflection of microcantilever beam will raise the local temperature of cantilever. This results in the resonance frequency shift due to the change in the effective stiffness of micro-beam. Therefore, studying the thermal effects on the microbeam is crucial when designing and employing microcantilever. In this study, a new modeling framework is presented for piezoelectrically driven atomic force microscopy (AFM). The piezoelectric layers are used as actuator and sensor attached on the top and bottom side of the cantilever. In our model, the local thermal effect due to laser beam has been also taken into account. The Hamilton’s principle is used to derive the governing equations.
A Study of PLA Crystallization During Solid-State Foaming
Authors: Wang Xiaoxi , Kumar Vipin , Li Wei
Published: May 2009

Polylactic acid (PLA) is a biodegradable semi-crystalline thermoplastic polymer that can be used in many applications such as tissue engineering scaffolds and packaging. The crystallinity of PLA is an important factor that affects its process-ability, mechanical strength, and biodegradability. The solid-state foaming of semi-crystalline PLA has been a subject of recent investigations. In this paper, crystallization through out the solid state foaming process was studied. It was found that the crystallization reaches the equilibrium once the gas sorption reaches the equilibrium. There are two main factors that will affect the PLA crystallization: gas sorption during the saturation stage and the heating and stretching during the foaming stage. Within the range of 2 to 5 MPa saturation pressures and 60 to 100 °C foaming temperatures, a maximum crystallinity of approx. 25% was observed in the foamed PLA. Effects of stretching and foaming temperature on crystallinity of foamed specimens were also investigated.
Simulation of Tensile Behavior in Friction Stir Welded and Superplastically Formed Titanium 6 Al-4V Alloy
Authors: Edwards Paul D. , Sanders Daniel G. , Ramulu M.
Published: May 2009

A hybrid numerical and experimental study was undertaken to evaluate the performance of as Friction Stir Welded (FSW) and Superplastically Formed Friction Stir Welded (SPF-FSW) Titanium joints. This paper presents the numerical models which were developed to simulate mechanical response of as FSW and SPF-FSW joints. The simulation results were then compared to experimentally determined behavior characteristics of the joints to assess the validity of the modeling approach. It was found that the numerical modeling approach presented here have simulated successfully the tensile behavior of a FSW joint agreeing with the experimental results. This method also adequately simulated the tensile behavior of a SPF-FSW joint, but due to geometrical influences, there are discrepancies between the numerical results and experimental observations.
Numerical Analysis of Crack Propagation and Life Estimation of Curtis Stage Blade of a Steam Turbine
Authors: Rodri´guez J. A. , Kubiak J. , Garci´a J. C. , Segura Jose´ A. , Sierra F. , Urquiza G.
Published: May 2009

During the operation of a turbomachine the parts most exposed to the alternative forces are the blades. The Curtis stage blades are then subjected to high alternative loads which may cause forced vibrations and these may fracture and fatigue the blades, affecting the integrity of the machine and causing its consequential shut down. In this paper the numerical analysis of crack propagation in Curtis stage blade subject to forced vibrations is presented. A finite element model of the Curtis stage blade was constructed. The natural frequencies, the steady and dynamic stresses were calculated according to life estimation. The stresses due to forced vibration were estimated using the alternative forces based in computed numerical fluid dynamics from a previous study.
Design and Fabrication of MEMS Based Microphone Module by Using 3D Chip-on-Chip Package
Authors: Lo Jeffery C. C. , Lee S. W. Ricky
Published: May 2009

Packaging of the MEMS based microphone is very important as the sensing diaphragm is very fragile. A suitable packaging method is required for the MEMS based microphone. In order to have a better understanding of packaging related issues of microphone, commercially available MEMS based microphone package is studied. Based on the preliminary study, a 3D Chip-on-Chip modulus is selected. The detail process flow of the mentioned package will be discussed in the following sections. Flip chip with lead free solder bumps are used in the proposed 3D Chip-on-Chip modulus. In contrast, wire bonds are used in the commercial MEMS based microphone for electrical connections while die attached is used to provide the mechanical support. The advantages of using flip chip over wire bond in both manufacturability and reliability aspects are discussed. Several MEMS based microphone packaging related issues are studied and evaluated. The detail fabrication and assembly process flow will be presented. A prototype package with MEMS device is fabricated. It can be shown that the proposed 3D Chip-on-Chip modulus is feasible for packaging MEMS based microphone.
Fabrication Process Development and Characterization of Polymethylhydrosiloxane (PMHS) for Surface-Modified Microfluidic Chips
Authors: Vijay Mukund , Ghandehari Ehson , Goedert Michel , Lee Sang-Joon J.
Published: May 2009

Microfluidic chips made of polymer materials such as polydimethylsiloxane (PDMS), polyimide, and cyclic olefin co-polymer have cost and manufacturing advantages over materials such as fused silica and borosilicate glass. While these materials have been extensively investigated, polymethylhydrosiloxane (PMHS) is an alternative that has a unique combination of properties in terms of UV transparency and potential for chemical surface modification. The present study investigates process development and characterization of PMHS as a new candidate material for microfluidic chip applications, in particular separation processes that would benefit from the ability to custom-engineer its surface conditions. This paper compares different approaches for fabricating microchannel features as well as options for enhancing the surface area of the channel walls. The fabrication methods include replication by casting over patterned molds, soft lithography casting, and material removal by laser ablation. Casting into solid form is achieved in 48-hours at 110 °C. Laser ablation is studied with energy dose varying from 2 mJ to 160 mJ per millimeter scanned, with channels approximately 100 microns wide occurring at 0.2 mJ/mm. Mechanical characterization is applied to quantify the hardness of cast PMHS, because fine-resolution features are limited by mold removal. PMHS samples have been measured to have a Shore A hardness of 46.2, similar to PDMS that is well-established in polymer microfluidic devices. Surface enhancement techniques including laser and plasma treatment are investigated for the prospective benefit of separation processes that require high surface-to-volume ratio. Spectrophotometry shows that PMHS exhibits transmittance even below 250 nm, which is favorable for sample analysis by UV absorption methods.
A Two-Liquid Electroosmotic Pump for Portable Drug Delivery Systems
Authors: Litster Shawn , Ha Byunghang , Kim Daejoong , Santiago Juan G.
Published: May 2009

Portable drug delivery systems present an opportunity to improve patient mobility and reduce drug dosage. Infusion pumps for drug delivery are heavily used in hospital and home care settings to administer a variety of therapies such as chemotherapy, antimicrobials, analgesia, anesthesia, and post-operative and chronic pain management. We are developing electroosmotic (EO) pumps for drug delivery applications. EO pumps offer active dosage control, are compact, use low power, and have no moving parts. We here explore a two-liquid EO pump that decouples the drug from the working electrolyte with a series of collapsible membranes and enables EO pumping of a wide variety of medications.
Characterization of Micro-Valves for Lab-on-Chip Device
Authors: Dutta S. , Banerjee D.
Published: May 2009

The objective of this study is to develop a portable hand held diagnostics platform for monitoring pollutants and water quality testing. We are developing a lab-on-chip (LOC) device for in-situ synthesis of gold nano-particles and for using a colorimetric peptide assay for water quality monitoring. The gold nano-particles are synthesized in-situ in our experiments. The gold nano-particles exhibit various optical properties due to their Surface Plasmon Resonance (SPR). These stabilized mono-disperse gold nano-particles are coated with bio-molecular recognition motifs on their surfaces. The stabilization and functionalization with bio-molecular recognition motif provides flexibility for various applications. For example, the gold nano-particles synthesized by this process are tested for their ability to be recognized by a surface coated with anti-Flg antibodies. The LOC consists of micro-wells housing different reagents and samples that feed to a common reaction chamber. The reaction products are delivered to several waste chambers in a pre-defined sequence to enable subsequent reagents/ samples to flow into the reaction chamber. Passive flow actuation is obtained by capillary driven flow (wicking). Dissolvable micro-structures are used as passive micro-valves that actuate at predefined intervals and do not require any external power source for actuation. The microfluidic chip (LOC) and the dissolvable microstructures are fabricated using soft lithography techniques. The passive valves are incorporated into the microfluidics platform by novel micro-fabrication and bonding techniques.
Robust Motion Generation for Vision-Guided Robot Bin-Picking
Authors: Leonard Simon , Chan Ambrose , Croft Elizabeth , Little James J.
Published: May 2009

This paper discusses work towards a vision-based solution to the problem of robot bin-picking. The problem of robot bin-picking is defined as searching for and recognizing a part among many lying jumbled in a bin such that the robot is able to grasp and manipulate the part. Despite decades of research in vision, robotics, and manufacturing, this problem remains open. Currently, in modern manufacturing, this seemingly simple task is performed by complex assembly lines or manual labor. The amount of efforts and costs associated with the current solutions to bin-picking is a testament to the importance of a new solution. The main objective of this research is a reliable and cost effective automated solution to the bin-picking problem encountered in manufacturing. As a broader contribution, this research also provides a robust visual servoing method that enables safe interactions between a robot and its environment. Our system uses visual feedback to generate tasks autonomously and to control the interaction of the manipulator with its environment. First, our system relies on robust vision-based object localization to generate three-dimensional pose hypotheses for each identified part. Then, the hypotheses are filtered according to the feasibility of their picking configuration. Finally, a trajectory is generated for a picking position. In this paper, we consider the specifications of the trajectory ensure that collisions with the bin and joints limits are avoided, while servoing the robot to the part. To ensure the reliability of the system, the procedure is tested in a simulation before being executed by a manipulator. Our experiments target the automotive industry and involve real engine parts a typical industrial robot and metal bin.
Numerical Analysis of Multiphase Flow in a Steel Oxygen Converter With Top and Bottom Blowing
Authors: Medina Dulce Y. , Barron Miguel A. , Hilerio Isaias
Published: May 2009

Combined blowing in the steelmaking basic oxygen converter is a technique that allows more agitation in the metal bath, and gives a fast decarburization rate, accelerated removal of impurities and chemical and thermal homogenization. In this work the multiphase flow in an industrial-like basic oxygen converter with top and bottom blowing is analyzed by means of Computational Fluid Dynamics software. Turbulence in the converter is simulated by means of the classical K-ε model given that this model yields more numerical stability during the integration for long times. Top jet velocities of Mach 1 and Mach 2, and 50 and 100 m s−1 of bottom injection velocities are used, and the results are compared with the conventional top blowing injection. Numerical results show that the combined blowing generates more agitation of the metal bath than that of the top blowing, however, from an operating viewpoint, combined blowing promotes that a significant volume of molten metal be expelled from the converter mouth.
Capillarity Effect on Two-Phase Flow Resistance in Microchannels
Authors: Rapolu Prakash , Son Sang Young
Published: May 2009

An experimental set-up is developed to investigate the effects of surface energy/surface wettability on characteristics of two-phase flow in microchannels. Two-phase (water and air) slug flow is established in entrance effect free microchannel test sections of various surface wettabilities. Pressure drop measurements and flow pattern detection by high speed visualization are employed to characterize the flow. Pressure drop of flow in hydrophilic channels is lesser than that of flow in hydrophobic channels. Significant change in contact line in advancing and receding interface section with surface wettability is observed.
Numerical Studies of Mixing in an Electroosmotically Stirred Continuous Micro Mixer
Authors: Kim Ho Jun , Beskok Ali
Published: May 2009

A continuous microfluidic mixer concept is developed by superposition of time-periodic electroosmotic flow on zeta potential patterned surfaces and pressure driven flow. Finite time Lyapunov exponents and filament stretching are utilized to quantify the chaotic strength, and to identify the chaotic and regular zones in the mixer at various operation conditions. Numerical solutions of the species transport equation are performed as a function of the Peclet number (Pe) at fixed kinematic conditions. Mixing efficiency is quantified using mixing index that is based on standard deviation of the scalar species distribution. The mixing length (lm) is characterized as a function of the Peclet number, and lm ∝ ln (Pe) scaling is observed under locally-optimum stirring conditions.
Modeling Continuous System Dynamics in SysML
Authors: Johnson Thomas A. , Jobe Jonathan M. , Paredis Christiaan J. J. , Burkhart Roger
Published: May 2009

In this paper, we present a formal approach to modeling continuous system dynamics in SysML using differential algebraic equations (DAE’s). To support model-based design, the Object Management Group has recently developed the Systems Modeling Language (OMG SysML™). The language is well-suited for modeling many different aspects of large-scale, multidisciplinary engineering projects. It allows systems designers to capture information concerning system requirements, tests, structures, functions, and behaviors. However, SysML lacks explicit support for modeling continuous system dynamics using DAE’s. Such models are important for representing system behavior resulting from energy or signal exchange between system components. We introduce support for modeling system dynamics in the form of a language mapping between SysML and Modelica, an equation-based, object-oriented behavioral simulation language. The bidirectional mapping provides support for creating system dynamics models in SysML that can exist alongside other SysML information models, but that can also be transformed into executable simulations by a Modelica solver. To illustrate the approach, we provide an example SysML model of a hydraulic pump.
Numerical Heat Transfer and Fluid Flow Modeling of a Nano-Robot Inside the Blood Stream of an Aorta
Authors: Ghassemi M. , Varmarzyar M. , Ebrahimi M. K. , Zare M.
Published: May 2009

The idea of nano-technology started in 1959. It has been used in different applications since its creation. One of its new areas of applications is in medicine. From medical instruments (i.e. sensors etc) to medical treatments nano-technology is playing a major role. Application of nano-robot inside human blood for health purposes is a promising area. The purpose of this study is to investigate the flow field and heat transfer modeling of a nano-robot inside the biggest human vein, Aorta. In our formulation of governing nonlinear partial differential equations, momentum and energy equations are applied to the blood and the nano-robot. The equations are solved by a computational fluid dynamic code. The velocity profile, pressure and temperature distribution of the nano-robot in direction of the blood stream as well as in opposite direction of the blood stream are calculated. Results are verified with a known experimental condition. Results show that the nano-robot does not disturb the blood stream significantly. Therefore it is safe to use such devices inside blood stream for medical purposes.