bluuebunny/crossref_metadata_2025 huggingface dataset:
Serial Microfluidic Device for Micro Droplet Trapping and Pairing
Authors: Gopalan Preethi , Ahn Byungwook , Oh Kwang W.
Published: May 2012

We propose a serial flowing microfluidic system for droplet generation along with a sequential trapping and pairing of micro-droplets. This device consists of three different functional regions: a flow focusing droplet generator; a single droplet trap region; and a pairing region. Our design is based on the principle of exploiting hydrodynamic resistance of the columnar structure in the microfluidic channel. By adjusting the flow rate and the fluid pressure inside the trapping area, the droplet trapping was precisely executed. The proposed method would continuously trap the droplets in the trapping area and when the reverse flow is applied, the droplet would be released and would enter the pairing chamber where it would be held until another droplet of different liquid to combine with it. Second droplet travels in the reverse flow direction and would be trapped in the pairing chamber to combine with first droplet.
Static Comfort Assessments for Ejection Seat Cushions in Three Different Rail Angles
Authors: Ojetola Akindeji , Onyebueke Landon , Winkler Edward
Published: May 2012

Aircrew members sit on ejection seats for a long period of time on operational missions. It is paramount for them to be as comfortable as possible within the constraints of this seat system to maximize their operational performance. Several health effects like numbness, pressure sore, low back pain, and vein thrombosis have been associated with protracted sitting. The cushion, and of late the installation rail angle are the only components of the ejection seat system that can be modified to reduce these adverse effects. This comprehensive static comfort assessment for ejection seats provides comparison between a variety of operational and prototype cushions (three in all: baseline cushion, honeycomb and air-cushion) and different installation rail angles (14°, 18°, and 22°) with 18° nominally used as the starting point. Three operational cockpit environment mockups with adjustable rail angle were built. Ten volunteer subjects, six females and 4 males, ages 19 to 35, participated in the comfort assessment. The volunteers fit within the JPATS cases 1–7 range of anthropometry, and each of them tested all cushions in all three installation rail angles. The volunteer clothing was similar the fighter pilot clothing ensemble (including harness). Each comfort assessment test lasted for six-hours, during which the subjects could not leave the seat and movement activities in the seat system were reduced as much as possible to reflect flight conditions. The subjective comfort survey and objective data such as seat pressure, blood pressure, and oxygen blood flow were gathered during the sitting period. The test results indicated that for objective methods, rail angle 22° persistently has a lowest seated pressure, while 18° has the highest pressure. An air-cushion has and maintains the lowest seated pressure, while a honeycomb cushion has the highest for all rail angles. When it comes to subjective comfort rating, the baseline cushion has the highest comfort rating, while the air-cushion has the lowest for all rail angles. The results for blood pressure and pulse rates are inconclusive. However, the oxygen blood flow (basal Sp02) favors the baseline cushion with the highest oxygen flow over the period of the testing, somewhat similar to the comfort rating.
Numerical Simulation of Deposition of Calcium Carbonate Particles Suspended in the Turbulent Cooling Water Flow
Authors: Izadi M. , Aidun D. K. , Marzocca P. , Tian L.
Published: May 2012

Calcium carbonate is predominantly present in cooling tower’s water and is usually the principal cause of hard water. This paper applies the modeling technique typically used for aerosol deposition to simulate the deposition process of calcium carbonate nano- and micro-particles suspended in turbulent cooling water flows. The mean turbulent velocity field and the fluctuating velocities are determined by the k-ε and RSM turbulence models by simulating the water flow in a typical heat exchanger horizontal tube. Commercial software (ANSYS FLUENT™ 12.1.4) is used for turbulence mean flow modeling and the simulation of turbulence fluctuations is performed by stochastic models. Particle deposition velocities are obtained for the particles with diameters in the range 0.01–50 μm by the k-ε and RSM models and compared to the deposition velocities calculated from semi-empirical correlations to investigate the effect of the turbulence model on the deposition velocity. Results show that the proposed numerical model can predict deposition velocity of micro-particles in water accurately and can be useful in determining the range of particle diameters in which the highest deposition velocity occurs. However, for nano-particles, the model’s results do not agree with the correlations due to the higher lateral turbulence fluctuations calculated by ANSYS FLUENT™ code. The proposed model can be useful for predicting fouling in industrial heat exchangers, for planning operations and cleaning schedules, and proposing efficient filtering processes for lowering deposition rate and cleaning costs.
Active Aeroelastic Control Using the Receptance Method
Authors: Singh Kumar Vikram , McDonough Laura A. , Mottershead John , Cooper Jonathan
Published: May 2012

The control and manipulation of dynamic instabilities, such as flutter, is termed as aeroelastic control and is extremely important in designing next generation flexible and maneuverable aircrafts. One of the goals of an aeroelastic control is to extend stable fight conditions for a large range of aerodynamic flow conditions. The associated control problem deals in adjusting and assigning the eigenvalues (which determine the natural frequencies and damping ratios) of the aeroelastic system for achieving the desired closed-loop behavior by active or passive means. In this paper, an active aeroelastic control problem, associated with the wing model, is formulated and eigenvalue assignment to achieve flutter free flight envelope is developed by using a new control methodology known as the Receptance Method. This method is entirely based upon transfer functions, typically obtained from a standard modal test by using actuators and sensors. This method has several advantages over traditional aeroelastic control approach which leads to state-space formulations. For example, it does not require the estimation of structural matrices (i.e. mass, stiffness and damping) as well as rational function approximations of aeroelastic influence coefficient matrices. The control gains are obtained without the knowledge of system matrices and purely from the receptance matrices. The feasibility study of this approach for aeroelastic control is considered here using several simple numerical aeroelastic systems. The control gains for eigenvalue assignments are obtained from receptance matrices and the performance of the controller is compared with those obtained by the state-space approach. Numerical examples associated with the eigenvalue assignment problems to adjust the natural frequency as well as damping ratio and to extend the flutter envelope by active means are presented. The actuator dynamics of the control surface and its effect on receptance based control is also studied. We envision that this new approach will facilitate an alternative method to address aeroelastic control problems and eventually will provide a practical solution for implementing active aeroelastic control.
Fabrication of Cost-Effective Polymer-Based Nanofluidic Device for Single Molecular Analysis
Authors: Wu Jiahao , Chantiwas Rattikan , Soper Steven A. , Park Sunggook
Published: May 2012

A nanochannel based single molecular sensor was fabricated in poly(methyl methacrylate) substrate by a single step imprinting process with a polymer stamp. The sensor structure consists of hierarchical multiscale patterns of an array of 90 nm (depth) × 190 nm (width) × 80 μm (length) nanochannels and microfluidic networks. In contrast to nanofluidic devices fabricated by high-end nanofabrication tools such as focused ion beam milling and electron beam lithography, this direct imprint process is more desirable for efficient and low cost fabrication. Moreover, due to the reduction of stress generated during imprinting, this polymer stamp imprinting process can also reduce the deformation (warping) in molded substrates, and prevent the damage of expensive nanostructured stamp as well.
Scaling Studies in Modeling for Compressive Strength of Thick Composite Structures
Authors: Chandraseker Karthick , Patro Debdutt , Nayak Ajaya , Quek Shu Ching , Yerramalli Chandra S.
Published: May 2012

Composite material usage in primary load bearing structures has continued to expand in aerospace, auto and wind energy industries. Large composite part thicknesses in some load bearing applications lead to defects during manufacturing. Typically, these defects are in the form of fiber waves, voids and delaminations. It is well known in the composite literature that composite compressive strength is a strong function of fiber alignment, and fiber waviness can cause failure due to fiber microbuckling and kinking or failure by splitting at the fiber/resin interface. A detailed micromechanical analysis of these wavy defects is needed to estimate the strength reductions due to presence of wavy defects in thick uni-directional (UD) laminates. For example, real composite part thicknesses in industrial applications are in the range of 40 mm-60 mm while individual fiber and resin layers are only a few microns in thickness. Hence, micromechanics finite element (FE) models involving individual layers require an enormous number of elements, which, in addition, scales poorly with the part thickness. Earlier studies on the effect of fiber waviness have focused on simplified homogenized models to study the effect of fiber waviness. However, such models cannot resolve local details such as inter-layer stresses that initiate resin yielding. In the present work, two modeling approaches are investigated — (i) a micromechanics approach in which individual fiber and resin layers are explicitly modeled, and (ii) a tow-level approach in which the fiber and resin properties are homogenized to generate effective properties of a tow. It is demonstrated that the two approaches lead to identical predictions of peak load for identical coupon dimensions. It is also shown that the peak compressive load plateaus beyond a certain value of coupon thickness. This information enables the modeling and testing of an actual thick part using a coupon of greatly reduced thickness and hence smaller number of elements in the computational model without compromising on the details afforded by a micromechanical model.
Sensor Fusion for Real-Time Condition Monitoring of Tool Wear in Surfacing With Fly Cutters
Authors: Hamade Ramsey F. , Ammouri Ali H.
Published: May 2012

A coherent artificial neural network, ANN, software program capable of real time analysis and decision-making is utilized in this work for the automatic detection and diagnostics of tool wear during a surfacing milling operation using a fly cutter. Several sensors were utilized to collect data indirectly related to wear: current measurements from the spindle and two (x, y) drive motors, three (x, y, z) components of cutting force, and acoustic emission. Furthermore, direct wear measurements were collected using image capturing and dimensional measurements of the worn location (not performed in real-time). As the inputs from these sensors were ‘fused’, the ANN utilized this multiple-sensor data to yield reasonable predictions of ‘good’, ‘used’, and ‘worn’ tools.
Driver Differentiation With Seat Settings: Part II—Feasibility Study for US Household
Authors: Flannagan Carol , Chen Shih-Ken , Litkouhi Bakhtiar
Published: May 2012

The addition of user-customizable features to automobiles increases the need to differentiate among drivers so that each driver’s custom settings can be automatically applied. Part 1 of this study modeled driver component positioning as a function of the stature difference between sharing drivers. To fully understand the feasibility of this approach to driver identification, we need to model the distribution of stature differences in the population of sharing drivers. Monte Carlo simulation is used to simulate both population variability in stature and positioning and the effect of initial conditions on positioning are included. The simulation of 10,000 households showed that for 87% of target pairs, differentiation performance of fewer than 2% errors can be achieved, even when the drivers share a vehicle equally (the most difficult differentiation scenario).
The Effect of Time-Varying Wind Direction on the Indoor Climate of a Naturally Ventilated Greenhouse
Authors: Kruger Sunita , Pretorius Leon
Published: May 2012

This paper presents a numerical investigation into the indoor climate of a four span naturally ventilated, four span greenhouse subject to a time-varying wind direction. The effect of transient wind conditions on the temperature and velocity distribution inside the greenhouse is numerically determined using Computational Fluid Dynamics (CFD). The research in this paper is an extension of work previously conducted on two-dimensional models of greenhouses. Current work concentrates on the three-dimensional effect of external winds. Results indicate that for a wind direction of 22.5 degrees, the microclimate at plant level varies throughout the length of the greenhouse. It was also found from transient simulations that even a slight change in wind direction have a pronounced effect on the indoor climate at plant level.
Optothermal Analyte Manipulation With Temperature Gradient Focusing
Authors: Akbari M. , Bahrami M. , Sinton D.
Published: May 2012

An optothermal analyte preconcentration method is introduced in this work based on temperature gradient focusing. The present approach offers a flexible, noncontact technique for focusing and transporting of analytes. Here, we use a commercial video projector and an optical system to generate heat and control the heat source position, size and power. This heater is used to focus a sample model analyte, fluorescent dye, at an arbitrary location along the microchannel. Optothermal manipulation of the focused band was demonstrated by projecting a series of images with a moving light band.
An Optimal Orthogonal Recharging Route Planner: A Multi-Robots, Multi-Rendezvous Recharging Scheme
Authors: Keshmiri Soheil , Payandeh Shahram
Published: May 2012

The issue of recharging a group of worker robots in their working environment has been tackled. For this purpose, a special purpose tanker robot has been devised with a planner, capable of generating recharging route that minimizes the cumulative sum of orthogonal distances of worker robots from their current locations to their corresponding recharging rendezvous locations along the recharging route (hence the term Orthogonal Recharging Route or ORR Planner). It has been proven that the ORR planner will result into a recharging route that minimizes the total worker robots distance traversal for recharging, irrespective of location of charging station/tanker. Experiments have been conducted to examine the practicality of the technique in contrast with scenarios of fixed charging station, as well as results of previous work based on Ordinary and Weighted Least Squares (OLS and WLS respectively) regressions. Results obtained in simulations are provided for illustrative comparison purpose among the different techniques.
Computational Assessment of Brittle Fracture in Glass-to-Metal Seals
Authors: Gullerud Arne , Emery John M. , Jamison Ryan
Published: May 2012

Glass-to-metal seals are widely used in engineering applications, but are often plagued by cracking and loss of hermeticity despite design efforts to avoid these problems. Standard computational approaches typically rely on under-refined meshes and rule-of-thumb approaches that are not always effective. This paper investigates improvements to current practice in glass-to-metal seal design. First, material models with more extensive temperature dependence are used to enhance the accuracy of residual stress prediction. Second, a Weibull-statistics approach is adopted for the prediction of the likelihood of failure. These approaches are then applied to a simplified seal geometry. The paper demonstrates that the application of these methods, especially the Weibull-statistics approach, have difficulties that need to be addressed before this proposed set of approaches can be effectively used for seal design. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
An Airship Design Methodology Based on Available Solar Energy in Low Stratosphere
Authors: Dumas Antonio , Trancossi Michele , Anzillotti Stefano
Published: May 2012

The actual applicative research concerning airships and their use as HAP (High Altitude Platforms for telecommunications and military use) presents new applicative hypothesis of these systems, also concerning energetic high quote production. Authors present the energetic balance of a high quote photovoltaic platform with capability of static hovering realized by electric powered propellers. This is the first step trough the design of the P. S. I. C. H. E. (Photovoltaic Space Island for Conversion of Hydrogen as Energy vector) airship concept: a stratospheric airship which could be considered a platform for hydrogen and oxygen production by photovoltaic. It investigates the behaviour of a similar platform operating at altitudes between 10 and 20 km, positioned at 45° latitude north [1, 2]. This paper analyses the design process for a High Altitude Platform based on photovoltaic energy caption, but the process could be generalized in order to be applied to any airship project. It is considers airship shapes equipped with large PV array that covers energy request during the day. Surplus in power supplies electrolyser equipments for hydrogen and oxygen production from water, which could be captured by atmospheric humidity or brought by an auxiliary airship. Hydrogen and Oxygen are compressed and stored in gas cylinders. With insufficient solar irradiance, with severe wind conditions and during the night, a fuel cell system fed by hydrogen and oxygen tanks supplies power requirements. The Standard Atmosphere Model is used to evaluate PV performance at various operative altitudes. A propulsion system with electric motors grants airship manoeuvrability and hovering. Energy balance of PV-hydrogen energy supply system has been analyzed for three airship shapes with equal volume with concern of overabundant hydrogen and oxygen production. Total weight and payload are calculated in relation to altitude. Storage tanks dimensions and products ground transportation frequency has been estimated. Hydrogen annual production for PV square meter has been evaluated in relation to ground production at the same latitude.
Investigation of the PLC Effect Using DIC
Authors: Storer Rebecca N. , Beaudoin Armand J. , Kurath Peter
Published: May 2012

In certain alloys non-homogeneous plastic flow is observed. A category of jerky flow, also called the Portevin-Le Chatelier (PLC) effect, is attributed to the competition between dislocation aging by solute atoms and plastic strain rate. In this study, the PLC effect was examined in an aluminum-magnesium alloy using digital image correlation (DIC) techniques. A cold rolling procedure was developed for Al5052-T0 specimens that resulted in repeatable jerky flow when tested in tension at nominal displacement rates that spanned three orders of magnitude. The tests were successful in producing repeatable propagating type bands of serrated flow, which resulted in serrations or stress drops on the stress versus time curve. Deforming specimens were photographed during testing, and the images were correlated using commercially available DIC software to determine local strains and local strain rates. The present study focuses upon type B, or hopping, bands. The DIC results revealed that the strain front moved along the length of the specimen and strains 1 to 2% higher were observed in the wake of the propagating bands. In addition, at least an order of magnitude increase in local strain rate corresponded to the band front as it moved through the specimen. At slower nominal displacement rates, the magnitude of the stress drops for type B bands was greater, but the number of stress drops was fewer for a given nominal displacement. The repeatability of this study shows that DIC provides an effective way to characterize this type of non-homogeneous or localized plastic flow.
Metrological Considerations on Ultrasonic Flowmeters
Authors: Marques da Silva R. Pitanga , Orlando A. Faro
Published: May 2012

An ultrasonic flowmeter is a non-intrusive device that employs the transit time of an ultrasonic signal to measure gas and liquid flow rate. With no moving parts, they are extensively used to measure the flow rates of hydrocarbon gases in applications that require a wide range of pressure (e.g.: custody transfer of natural gas). But despite many technological advances, ultrasonic meters still need metrological assessment. Velocity profiles—fundamental to calculate flow rates—are constructed by making use of the well-known Gauss’ integration technique that depends, to a large extent, on a suitable choice of an orthogonal polynomial. The Gauss-Legendre’s quadrature is the most popular among manufacturers. In order to reduce uncertainties when the velocity profile has few points, the discretization error must be quantified. The paper presents simulations made with Gauss’ and Chebyshev’s quadratures for turbulent flow in smooth pipes and compares them with the theoretical profile. Some aspects of metrological reliability of ultrasonic meters are also discussed.
Micro Snap-Fits for Latching 3D MEMS Assemblies
Authors: Shaar N. S. , Barbastathis G. , Livermore C.
Published: May 2012

This paper reports the design, fabrication and demonstration of micro-scale mechanical latches (micro snap-fits) for assembling 3D micro-structures from 2D patterned precursors. The latches consist of pairs of pointy arrowhead-like features mounted on cantilevers, on one membrane, and corresponding slits in the mating membrane. As the membranes are pushed together, the cantilevers bend elastically and squeeze the arrowhead tips through the slits to latch onto the back side of the mating membrane. The latches are reversible, enabling reconfigurable assembly. They are also designed to have no backlash, enabling precise positioning of the assembled structures. An analytical model of the latches was used to design the profile of the arrowheads subject to the geometrical constraints imposed by the alignment system. The micro snap-fits were demonstrated by assembling a corner-cube from two folded flat panels with the substrate serving as the third side.
Methanol Crossover in Direct Methanol Fuel Cells for Portable Applications: Achievements and Challenges
Authors: Ahmed Mahmoud , Ali Ahmed Hamza H. , Dincer Ibrahim
Published: May 2012

One of the major obstacles that currently prevent the widespread applications of DMFCs is the methanol crossover through the proton-exchange membranes (PEM). The present paper discusses the influence of different operating parameters, such as concentration of methanol, pressure, temperature, thickness and equivalent weight of membrane and catalyst morphology, on methanol crossover. It also discusses the development of PEM for DMFC. The effect of methanol crossover on DMFC performance is presented. The discussion of findings and recommendations for future research are presented.
Thermally Activated Protective Systems: Material Considerations for Improved Flash/Flame Protection
Authors: Little Benjamin J. , Arnas A. O¨zer
Published: May 2012

This paper is based on an effort to increase the protection from thermal and flash/flame threats due to explosion. The relatively recent threat of Improvised Explosive Devices, IEDs, the large thermal energy associated with them, as well as the secondary fires has prompted an investigation into whether the personal protective equipment available to the individual soldier provides adequate protection from injury. This is a continuation of a previous paper that investigated the full extent of the threat posed by explosions. The research included a profile of the thermal properties of the threat, typical injuries associated with explosions, as well as several possible means of alleviating the dangers. One means that was suggested was the use of intumescent materials. These are materials that expand when exposed to heat, thus increasing the distance between the threat and the person as well as altering their thermal conductivity to make them more resistant to burn. Using this suggestion, in this paper we seek to determine the feasibility of using these materials in a protective garment. It factors in soldier concerns of durability, comfort, et cetera but focuses mainly on the heat transfer aspects of the material.
Comparison Between Numerical Simulation and Experimentation of Asymmetrical Three-Roll Bending Process
Authors: Feng Zhengkun , Champliaud Henri
Published: May 2012

Three-roll bending processes are widely used in metal forming manufacturing due to simple configurations. Asymmetrical three-roll bending is one of the processes. This paper deals with the simulation analyses based on the finite element method for cylindrical production. The components of the roll bending machine, such as the rolls were assumed to be rigid bodies and the 4-node shell elements were used in the modeling. The tensile test of the material was simulated to determine the elasto-plastic material model of the plate. Automatic node-surface contacts were chosen for the interfaces between the plate and the rigid bodies. The nonlinear equations which represent the structural dynamics with large displacement were resolved using explicit time integration. The simulations were performed under the well-known ANSYS/LS-DYNA environment. The numerical results agree well with the experimental ones.
Control of a Standing-Wave Thermoacoustic Refrigerator
Authors: Ryan Tim , Schaefer Laura A. , Vipperman Jeffrey S.
Published: May 2012

A demonstration thermoacoustic refrigerator was used to test the effectiveness of three operating frequency control schemes. The goal was to determine which control scheme would be most beneficial in terms of efficiency when a driver and resonator are mismatched as may be the case where manufacturing tolerances are involved. The first control scheme was a phase-locked loop, which is the type of control most often used in the literature; the second and third were a gradient ascent algorithm applied to root-mean-squared acoustic pressure and time-averaged acoustic power supplied to the resonator, respectively. The controllers, each operating on a different parameter associated with a strong thermoacoutic effect, were simulated using an identified model of the plant, and adjustments were made to the controller parameters. Finally, the controllers were applied to the test bed device. The performance comparison of the controllers was based on thermoacoustic efficiency, electroacoustic efficiency, and electrothermal efficiency. The phase-locked loop was found to perform better thermoacoustically, but the acoustic pressure gradient ascent control performed better in terms of electroacoustic and electrothermal performance. The acoustic power gradient ascent controller resulted in the thermoacoustic core producing the most steady-state cooling power.
The Boiler Tech Challenge: A Fun Competition and Recruiting Tool for Engineering Technology Programs
Authors: Fuehne Joseph P. , Phillips Julie , McKinney Anji
Published: May 2012

Project Lead The Way, a pre-engineering curriculum for secondary students, has gained in popularity and importance at secondary institutions in the Region 9 workforce area in south central Indiana. The Purdue College of Technology in Columbus, Indiana stands to benefit from this effort by attracting these students to its programs, which have been enrollment-challenged in recent years. One possible recruiting tool instituted by the College of Technology in Columbus is the “Boiler Tech Challenge” for Project Lead the Way students throughout the region. Nearly 200 students from high schools around the region assembled at the Purdue College of Technology site in Columbus. There were teams of 4 students who needed to solve one of five possible challenges. With a space theme, the teams needed to design and build a space station tower to withstand a certain weight, build and assemble a spacesuit for one of the team members to wear, use a CAD tool to design a space station, design and build a pneumatic lift system to assist in the production of hydroponic vegetables in the space station, and design and build a carbon dioxide scrubber/filter to clean the air on a command module. This last challenge is similar to the situation encountered by the astronauts of Apollo 13. A maximum of 10 teams (no more than 4 team members per team) do each challenge and are given two hours to complete the challenge. Prizes are given to the winners. Other sessions throughout the day-long event include information sessions about the College of Technology in Columbus, a presentation by an engineer associated with the space program, and lunch. This work provides more details about the event and includes survey results of the participants. The initial event brought approximately 160 high school students to the Purdue College of Technology campus in Columbus and was a great recruiting tool.
The Effect of Temperature on the Etch Rate and Roughness of Surfaces Etched With XEF2
Authors: Butner Joseph , Leseman Zayd C.
Published: May 2012

In this work we present results from a pulsed etching system with XeF2 for an expanded temperature range while at the same time determining the roughness of the substrate left behind. The experimental apparatus used for the work presented in this paper is capable of temperature ranges from approximately 100 to 800 K. Data was taken at a constant etching pressure of 1.2 Torr so the effect of temperature on roughness and etch rate could be studied. Etch rates and surface roughnesses were characterized using a vertical scanning and phase shifting interferometer, respectively.
A Method to Improve the Illumination Effect in an Underwater Environment
Authors: Ji Yingfeng , Perez Ronald A. , Amano Ryoichi S.
Published: May 2012

There are some innate shortcomings for traditional underwater observation system due to camera/light’s rigid-fixed connection with carrier vehicle such as ROV (Remotely Operated Vehicle)/AUV (Autonomous Underwater Vehicle). One of these is that the clearance of video image is seriously corrupted since the backscatter of water/particles is not overcome using fixed light source. To make up the deficiency, multi-light sources have to be adopted as a traditional approach. In this paper, a Master-Slave coordinated architecture was created and developed to provide a solvable scheme for improving illumination consequence. The illumination geometry between a camera and a light can dynamically be coordinated so that the backscatter which is the culprit blurring the target observed can be greatly decreased. The light source can follow up the moving target which the camera captures based on the numerical simulation results. The proposed observation system is especially suitable for our research purpose, where an agile system is needed for the observation of small range in Lake Michigan. The dynamic and hydrodynamic models used in this paper can be found in [1]. The control algorithms to be employed to evaluate this proposed method in this paper can be referred to [2–3].
Effects of Gears, Bearings, and Housings on Gearbox Transmission Shafting Resonances
Authors: Hambric Stephen A. , Shepherd Micah R. , Campbell Robert L.
Published: May 2012

Gear noise, comprised of tones centered around gear meshing frequencies, is transmitted through driveshafts, bearings, and transmission housings. Gear noise transmission is amplified, sometimes strongly, by modes of vibration of the shafting. The shafts of the input and output gears vibrate like beams at low to mid frequencies. The resonance frequencies and vibration patterns of these beam-like modes depend strongly on the shaft boundary conditions, which in turn depend on the impedances of the bearings, and of the transmission housing. In this paper, we present simulated and measured modes of the input and output shafts of a single stage spur gear system mounted in a rectangular metal gearbox. The impedances of the gears, bearings, and housing are added in sequence and the effects on the fundamental mode shapes and frequencies are shown. The bearing impedances have the largest effects on the shafting modes, increasing the resonance frequencies significantly, along with spreading the frequencies of similar mode types. Including the housing impedances at the bearing locations reduces slightly the spread of shaft mode frequencies.
Impact of Ethanol Content on Full-Load Combustion Behavior and Engine Control Unit Response for a Direct-Injection, Spark-Ignition Engine
Authors: Ickes Andrew M. , Wallner Thomas
Published: May 2012

With its high octane number and potentially favorable greenhouse gas and energy balance characteristics, ethanol offers potential to replace portions of gasoline as a transportation fuel. System optimization to utilize the increased knock resistance and evaporative cooling effect of ethanol can increase the performance and efficiency of spark-ignition engines. Though basic engine emissions and performance effects of ethanol fuel blends have been widely reported, limited studies have examined the details of combustion behavior and the interplay between fuel ethanol content and the behavior of the engine control system. This paper quantifies the response of a production engine control unit to ethanol fuel blends, along with the subsequent combustion behavior and resulting engine performance at high-load operating conditions. Steady-state testing is conducted on a modern direct-injection, spark-ignition, four-cylinder engine using a base engine calibration at full-load (wide-open throttle) conditions across a range of engine speeds from 1500 to 4000 rpm. Test fuels include gasoline, neat ethanol, and an intermediate blend of gasoline and ethanol. A combination of low-speed engine measurements and crank angle based cylinder pressure measurements are used to demonstrate the impact of increasing fuel ethanol content on engine control parameters. Ethanol’s increased knock resistance, demonstrated by its higher octane number, compared to gasoline makes combustion less susceptible to knock as ethanol fraction in the fuel increases. Accordingly, less spark retard is required to avoid knock at high engine load, translating to higher fuel conversion efficiency and increased specific power output. This effect is explored within the framework of a production engine calibration which uses active knock-avoidance feedback control. The relative contribution between a more aggressive engine calibration and increased fuel-evaporation charge-cooling to the increased efficiency and power resulting from increasing fuel ethanol percentage is also characterized.
Compliant Micromixers
Authors: Dankovic Tatjana , Feinerman Alan
Published: May 2012

We have developed a novel fabrication technique for a passive, continuous flow micromixer with laminar flow. The device is made by welding thin thermoplastic sheets using a simple manufacturing procedure which reduces the total cost of the device, and enables frequent changes to the design as necessary. Two types of mixers were made, one with obstacles in the mixing channel to induce the forming of vortices, and the other having serpentine design. For both mixer designs we made a range of mixing chamber sizes to examine the efficiency of the mixing process in respect to available mixing length. In experiments we used two different colored water solutions to inject at the device inlets. The flow rate of the fluids was controlled by Cole Parmer Instruments syringe pump and the observed colored patterns are recorded using Digital Blue™ QX5 microscope. As the flow rate was changed in experiments from 0.01 to 100 microliter/min, the mixing was accomplished further down the channel and in some cases was not completed within the mixing chamber. However the relation between mixing length and flow rate (Reynolds number) is not linear and after certain value of Reynolds number the mixing is completed at a shorter distance from the inlets then expected. Our experimental results with larger devices show this non-linearity, while for the devices of smaller size that was not observed.
What Engineering Designers Leave Behind: Developing a Cognitive Coding Scheme for Student Design Journals
Authors: Westmoreland Sophoria , Schmidt Linda C.
Published: May 2012

Some historically successful engineering inventions have been designed by trial and error as was the famous case of Thomas Edison’s light bulb. No contemporary design researcher would advocate a tedious, trial-and-error methodology as the basis for engineering practice. The 21st century engineer is expected to create innovative solutions to real world problems with limited resources and limited time. Successful engineering design methods are those that substitute trial-and-error with practice-based guidance (e.g., TRIZ), mathematical analysis (e.g., optimization), general problem-solving strategies (e.g., functional decomposition and synthesis), or good cognitive thinking strategies (e.g., Synectics). This research is placed in the last category, studying the cognitive processes that can be observed in recorded work of engineering designers. This study is the first step in research intended to go further into the designers mind and reveal new insights about the design process. This paper presents a cognitive coding scheme model to organize and categorize designer “thinking” as recorded in design documentation. The product of this research can be used to instruct curriculum on teaching the design process for students and professional engineers.
Automatic Micropart Re-Orientation Through Visual Tracking for Automated Micro-Assembly
Authors: Chu Henry K. , Mills James K. , Cleghorn William L.
Published: May 2012

The process of microassembly often involves the manipulation and grasping of complex micro-sized objects. These micro-objects are generally initially placed at random orientations in the plane when transferred to an assembly workstation. The part orientations must be corrected in order for the gripper to grasp them. Visual monitoring feedback is commonly used to assist in the re-orientation and manipulation process. However, due to the very limited field of view of imaging systems used in micro-assembly, the target micro-object may not remain within the viewable area during the reorientation processes. This paper presents an integrated controller algorithm to automatically rotate micro-objects to the desired orientation in the plane for grasping. This novel algorithm incorporates the technique of dynamic tracking to prevent the target micro-object from shifting outside of the viewable area during the re-orientation process. As the micro-object is rotated to correct its orientation, the algorithm will evaluate the required translational inputs in order to maintain the micro-object within the field of view. To minimize the delay due to feedback control, the proposed algorithm employs the principle of Kaiman filter estimation to track and project the motion at the next sampling interval. The proposed algorithm was evaluated experimentally with a microassembly operation using an in-house micro-manipulator. Results from the experiments showed that the proposed tracking algorithm was capable of tracking and maintaining the targeted micropart at the specified location with an error of within +/−15 pixels.
System Analysis of Thermochemical-Based Biorefineries for Co-Production of Hydrogen and Electricity
Authors: Braun Robert J. , Hanzon Luke G. , Dean Jered H.
Published: May 2012

Fuels derived from biomass feedstocks are a particularly attractive energy resource pathway given their inherent advantages of energy security via domestic fuel crop production and their renewable status. However, there are numerous questions regarding how to optimally produce, distribute, and utilize biofuels such that they are economically, energetically, and environmentally sustainable. Comparative analyses of two conceptual 2000 tonne/day thermochemical-based biorefineries are performed to explore the effects of emerging technologies on process efficiencies. System models of the biorefineries, created using ASPEN Plus®, include all primary process steps required to convert a biomass feedstock into hydrogen, including gasification, gas cleanup and conditioning, hydrogen purification, and thermal integration. The biorefinery concepts studied herein are representative of ‘near-term’ (ca. 2015) and ‘future’ (ca. 2025) plants. The ‘near-term’ plant design serves as a baseline concept and incorporates currently available commercial technologies for all non-gasifier processes. The ‘future’ plant design employs emerging gas cleaning and conditioning technologies for both tar and sulfur removal unit operations. Gasifier technology employed in these analyses is centered on directly-heated, oxygen-blown, fluidized-bed systems. Selection of the gasifier pressurizing agent (CO2 v. N2) is found to be a key factor in achieving high hydrogen production efficiency. Efficiency gains of 8-percentage points appear possible with CO2 capture using Selexol or Rectisol-type processes. A 25% increase in electric power production is observed for the ‘future’ case over the baseline configuration due to improved thermal integration while realizing an overall plant efficiency improvement of 2 percentage points. Exergy analysis reveals the largest inefficiencies are associated with the (i) gasification, (ii) steam and power production, and (iii) gas cleanup and purification processes.
Finite Element Analysis of a Phononic Crystal at Gigahertz Frequencies
Authors: Alaie Seyedhamidreza , Mousavi Arash K. , Su Mehmet , Leseman Zayd C.
Published: May 2012

In this paper, the vibrational behavior of a phononic crystal is studied at gigahertz frequencies. The phononic crystal is comprised of a silicon slab with tungsten inclusions filtering out waves within the frequency range of 0.7 GHz to 1.1 GHz. Two-dimensional harmonic finite element analysis (FEA) is employed to model the transmission of stresswaves launched from a transmitter and passing through the crystal. The numerical results are compared with another prevalent numerical method, finite difference time domain (FDTD), as well as with experimental results. Comparisons made between the numerical approaches and experimental approach, show that the harmonic finite element analysis agrees well with experiment and potentially can explain the experimental results more precisely than FDTD. This more favorable comparison is attributed to a resonance that occurs between the transmitter and the phononic crystal.
Mechanical Behavior of Porcine Pulmonary Artery
Authors: Zhao Shijia , Gu Linxia , Hammel James M. , Lang Haili
Published: May 2012

Proper characterization of the material properties of pulmonary arterial tissue is needed for many medical applications. The objective of this study was to investigate the stress-strain relationship and characterize the nonlinear elastic behavior of porcine pulmonary arteries; thus, uniaxial tension tests and cyclic loading-unloading tests were conducted on healthy porcine pulmonary arterial tissue. In these experiments, pulmonary arteries from different piglets and a commercial pulmonary valved conduit, called “Contegra 200”, were subjected to uniaxial tension. Results demonstrated a higher stiffness along the circumferential direction than the axial direction. The “Contegra 200” was much suffer than real pulmonary arterial tissue along the axial direction and had a similar stiffness to natural tissue along the circumferential direction within physiological stretch ranges, which is less than 40% strain. Elastic hysteresis was observed from cyclic loading-unloading tests, which indicates that more energy was required during the loading than the unloading. A nonlinear hyperelastic model based on second order polynomial constitutive equation was derived from average values of the test data along both axial and circumferential directions. The material model could be used in numerical analysis of pulmonary arterial response and facilitate the design of intravascular devices.
Mode II Measurements for Stiction Failed MEMS Devices
Authors: Kashamolla Maheshwar R. , Goettler Drew F. , Mousavi Arash K. , Leseman Zayd C.
Published: May 2012

Among MEMS devices, the most common type of failure is stiction. Stiction is the unintended adhesion between two surfaces when they are in close proximity to each other. Various studies have been conducted in recent years to study suction. Our research group has shown the in-service repair of the suction failed MEMS devices is possible with structural vibrations. In order to further understand this phenomenon and better predict, theoretically, the onset of repair we have constructed an apparatus to determine the Mode I, II, and III interfacial adhesion energies of MEMS devices failed on a substrate. Recently we have developed a nonlinear model to measure the Mode I interfacial adhesion energies accurately. Using the same experimental apparatus we used earlier to determine the Mode I interfacial adhesion energies, we measure the Mode II interfacial adhesion energies. The proposed experimental method for measuring the Mode II interfacial adhesion energies for suction failed MEMS devices uses a microcantilever beam (1500 μm long, 10 μm wide, and 2.6 μm thick) attached to MEMS actuator with fixed-fixed beam flexure. Deflection of the spring is measured with a vernier scale of the actuator. Then a nonlinear elastic model of the fixed–fixed beam flexure is used to determine the interfacial adhesion energy between the failed microcantilever beam and the surface. In this work, we report our initial results for the interfacial energies from Mode II type failures. A critical strain energy release rate, for Mode II, is found to be G ≤ 549 μJ/m2.
Modeling of Flexible Fiber Motion and Orientation in Simple Shear Flow: A Comparison Between the Rod-Chain Model and Jeffery’s Equation
Authors: Zhang Cong , Jack David A.
Published: May 2012

This paper compares results from the the rod-chain model with those from results based on Jeffery’s equation. A concept of critical buckle aspect ratio is employed to define the rigidity or flexibility of a fiber, above which point a fiber is flexible enough to be bent and twisted. When a fiber has an aspect ratio less than the critical buckle aspect ratio, fiber motion predicted by the rod-chain model corresponds perfectly with that of Jeffery’s equation. The trajectories of a single rigid fiber with different initial orientations are shown by the rod-chain model, which are in line with what Jeffery’s equation predicts. Results are also shown for the configuration of a single flexible fiber at various times under a pure shearing flow. The “blind area” of the rod-chain model is discussed.