bluuebunny/crossref_metadata_2025 huggingface dataset:
Flexible Microfluidic Devices With Three-Dimensional Interconnected Microporous Walls
Authors: Yuen Po Ki , DeRosa Michael E.
Published: August 2012

Microfluidics is emerging as one of the fastest growing fields for chemical and biological applications. The demand has also increased for methods of fabricating low-cost prototype microfluidic devices rapidly with compatible materials and novel functional attributes. One attractive feature that can be incorporated into microfluidic devices is a porous membrane or porous channel wall [1]. Devices with such features can potentially be used for multiphase catalytic reactions in chemical and pharmaceutical applications similar to the gas-liquid-solid hydrogenation reactions reported by Kobayahi et al. [2] or gas-liquid syntheses by Park and Kim [3].
An Assessment, Definition, and Determination of the Minimum Uncut Chip Thickness of Microcutting and Impact on Machining New Powder Metallurgy Nickel-Based Superalloys
Authors: Shi Z. Y. , Liu Z. Q. , Guo Y. B.
Published: August 2012

The uncut chip thickness is comparable to the cutting edge radius in micromachining. If the uncut chip thickness is less than a critical value, there will be no chip formation. This critical value is termed as the minimum uncut chip thickness (MUCT). Although minimum uncut chip thickness has been well defined in orthogonal cutting, it is often poorly understood in practical complex turning and milling processes. This paper presents an analysis of the state-of-art research on minimum uncut chip thickness in precision micro-machining. The numerical and experimental methods to determine MUCT values and their effects on process mechanics and surface integrity in microcutting will be critically assessed in this paper. A set of definitions of minimum uncut chip thickness for three-dimensional turning and milling processes are presented. In addition, a detailed discussion on the characteristics of different methods to determine minimum uncut chip thickness and several unsolved problems are proposed for the future work.
A Model for Relating Environmental Variation to Water Permit Violations at Thermoelectric Facilities in the Taunton River Watershed
Authors: Sheldon Seth , Frankic´ Anamarija
Published: August 2012

An original model is presented that relates the rate of National Pollutant Discharge Elimination System (NPDES) water use permit violations and reduced capacity events (dial-back) at once-through cooled thermoelectric power plants to electricity demand and ambient environmental conditions using historical data. 31 percent of U.S. generation capacity is composed of thermoelectric facilities that use once-through (open loop) cooling [1]. Open loop systems have substantial water demands, which put energy facilities and downstream ecosystems at risk during extreme climate events (e.g. heat waves, droughts) [2]. During such events, power plant managers must decide to either dial back electricity generation or violate their water permits by using too much water or by discharging it at too high a temperature. Withdrawal rate and effluent temperature violations can be costly for energy utilities and are detrimental to the biota of receiving waters [3].
Preconcentration of Cardiac Proteins in a Cascade Microchip
Authors: Hossan Mohammad R. , Jubery Talukder Z. , Bottenus Danny R. , Dutta Prashanta , Ivory Cornelius F. , Dong Wenji
Published: August 2012

Concentration of bio-molecules prior to detection is very critical in the development of an integrated, multifunctional lab-on-a chip device for detection of ultra trace molecules from complex biological fluids such as serum, urine, or saliva. In this work, the preconcentration of a clinically relevant biomarker, cardiac troponin I (cTnI), is demonstrated in a cascade microfluidic channel using cationic isotachophoresis (ITP). The cascade chip is formed on PMMA (poly methyl methacrylate) with gradual changes in size both in width and depth direction to achieve a 100× reduction in overall cross sectional area between inlet (anode) and outlet (cathode) sections. The ITP experiments were conducted with two fluorescent proteins, FITC (Fluorescein isothiocyanate-conjugated) albumin and cTnI labeled with Pacific Blue. Potassium ions were used as the leader and hydronium ions were used as the terminator for these cationic ITP experiments. The microchip ITP demonstrates that it is possible to increase the concentration of cTnI by 10,000 folds using a potential drop of 400 V across a 3.5 cm long microchannel. The reduction in cross sectional area facilitates additional concentration gain, as the proteins migrate through cascade microchannel under discontinuous electric field and stacked into nearly pure zones.
A Modified Cost Function Based Optical Tomography Reconstruction Algorithm Optimized for Finite-Elements Methods
Authors: Balima Olivier , Favennec Yann , Boulanger Joan , Charette Andre´
Published: August 2012

In optical tomography, the optical properties of the medium under investigation are obtained through the minimization of an objective function. Generally, this function is expressed as a discrete sum of the square of the errors between measurements and predictions at the detectors. This paper introduces a continuous form of the objective function by taking the integral of the errors. The novelty is that the surfaces of the detectors are taken into account in the reconstruction and a compatibility is obtained for all finite element formulations (continuous and discontinuous). Numerical tests are used to compare the reconstructions with both objective functions. It is seen that the integral approach leads to low values of objective functions those reconstructions may be affected by rounding errors. Scaling of the objective function and its gradient shows that both methods give comparable accuracy with an advantage to the continuous approach where the integral acts as a filter of noise.
Milling Burr Size Estimation Using Acoustic Emission and Cutting Forces
Authors: Niknam Seyed Ali , Tiabi Azziz , Zaghbani Imed , Kamguem Rene , Songmene Victor
Published: August 2012

Burr formation is one of the main concerns usually faced by machining industries. Its presence leads to additional part edge finishing operations that are costly and time consuming. Burrs must be removed as they are source of dimensional errors, jamming and misalignment during assembly. In many cases burrs may injure workers during handling of machined part. Due to burr effect on machined part quality, manufacturing costs and productivity, more focus has been given to burr measurement/estimation methods. Large number of burr measurement methods has been introduced according to various criteria. The selection of appropriate burr size estimation method depends on number of factors such as desired level of quality and requested measuring accuracy. Traditional burr measurement methods are very time consuming and costly. This article aims to present empirical models using acoustic emission (AE) and cutting forces signals to predict entrance and exit burrs size in slot milling operation. These models can help estimating the burrs size without having to measure them. The machining tests were carried on Al 7075-T6 aluminum alloy using 3 levels of cutting speed, 3 levels of feed rate, 3 levels of cutting tool coating and 2 levels of depth of cut. Mathematical models were developed based on most sensitive AE parameters following statistical analysis, cutting forces and their interaction on predicting the entrance and exit burrs size. The proposed models correlate very well with the measured burrs size data.
Estimation of Erythrocyte Deformability Using a Viscoelastic Model With Two Degrees of Freedom
Authors: Mori Tatsuya , Saito Takashi
Published: August 2012

An erythrocyte is represented using a viscoelastic model with two degrees of freedom, where a spring was connected parallel to a dashpot to estimate quantitatively the dynamic deformability. To identify such parameters as the elastic modulus and viscous damping coefficient of the model, erythrocytes were deformed using a periodical shear flow field. Displacement of the center of gravity ΔG and the deformation quantity of major axis ΔL were obtained from time series of images. In this paper, erythrocytes from a normal subjects were treated with glutaraldehyde to create variations in hardness and deformability. Both of the data series are periodic on movement and deformation of erythrocytes. Based on the experimental data, parameters of the viscoelastic model were identified. The estimation method of dynamic deformability of erythrocytes was examined.
Numerical Simulation of Melting/Solidification Phenomena Using a Multi–Fluid Modeling Approach
Authors: Srinivasan Vedanth
Published: August 2012

In this article, a fixed-grid finite volume approach to simulate the convection-dominated solidification/melting process is presented. An Eulerian multi–fluid modeling approach is employed to track the phase change interface by obtaining solutions to governing volume fraction, momentum and energy transport equations. The liquid-solid interfacial phase transfer effects are modeled using a novel mass transfer function incorporating the latent heat modification due to the phase change process. The alterations in the local phasic fractions and the resultant cellular latent heat is correctly realized using a source term approach within a homogeneous enthalpy modeling framework. The model fully implemented within the commercial CFD code AVL FIRE® V2010 is tested and validated using a (1) classical 1D Stefan’s problem (2) melting of gallium (3) tin solidification scenario. In addition to the mass, momentum and energy solutions, transport of species within multi-component liquids is made possible, thereby allowing means for efficient and accurate coupling between the temperature and concentration fields within the system. Description of the phase change fronts, the local velocity and temperature fields are discussed in detail. Results from the simulations are compared against experimental data wherever available. Discussions pertaining to the applicability of the model and its robustness are elaborated within the article.
Traction Forces During Cell Migration Predicted by the Multiphysics Model
Authors: Han Sangyoon J. , Sniadecki Nathan J.
Published: August 2012

Cells rely on traction forces in order to crawl across a substrate. These traction forces come from dynamic changes in focal adhesions, cytoskeletal structures, and chemical and mechanical signals from the extracellular matrix. Several computational models have been developed that help explain the trajectory or accumulation of cells during migration, but little attention has been placed on traction forces during this process. Here, we investigated the spatial and temporal dynamics of traction forces by using a multiphysics model that describes the cycle of steps for a migrating cell on an array of posts. The migration cycle includes extension of the leading edge, formation of new adhesions at the front, contraction of the cytoskeleton, and the release of adhesions at the rear. In the model, an activation signal triggers the assembly of actin and myosin into a stress fiber, which generates a cytoskeletal tension in a manner similar to Hill’s muscle model. In addition, the role that adhesion dynamics has in regulating cytoskeletal tension has been added to the model. The multiphysics model was simulated in Matlab for 1-D simulations, and in Comsol for 2-D simulations. The model was able to predict the spatial distribution of traction forces observed with previous experiments in which large forces were seen at the leading and trailing edges. The large traction force at the trailing edge during the extension phase likely contributes to detachment of the focal adhesion by overcoming its adhesion strength with the post. Moreover, the model found that the mechanical work of a migrating cell underwent a cyclic relationship that rose with the formation of a new adhesion and fell with the release of an adhesion at its rear. We applied a third activation signal at the time of release and found it helped to maintain a more consistent level of work during migration. Therefore, the results from both our 1-D and 2-D migration simulations strongly suggest that cells use biochemical activation to supplement the loss in cytoskeletal tension upon adhesion release.
The Value of Geographic Diversity of Wind and Solar: A Vector Analysis
Authors: Diakov Victor , Short Walter
Published: August 2012

The variability of wind and solar is perceived as a major obstacle in employing otherwise abundant renewable energy resources. Based on the available geographically dispersed data for the WECC U.S. area (excluding Alaska) and eastern U.S., we analyze to what extent the geographic diversity of these resources can offset their variability. It is common to discern baseload (i.e. constantly employed cheaper power generation, as from nuclear and coal plants) from more expensive dispatchable power sources which help meet variable electric load. The spot electricity price depends on the difference between the load and baseload. With significant amounts of power coming from wind and solar, we use generation with low variable cost (GLVC) to include baseload and wind/solar generation. The GLVC will then become variable as well. The electricity price, however, will be determined by the difference between load and GLVC. While the details of future electricity spot-pricing are harder to predict, the overall trend will remain: a higher hourly difference between load and the low-variable-cost generation increases the electricity price. This difference can serve as an approximate measure of the (hourly) revenue from producing electricity. Currently, the variable load follows fairly well defined daily and weekly load cycles. Significant amount of wind-produced power will inevitably alter the cyclic nature for the variable load time-dependence. Additionally, wind and solar farms generation profiles may be expected to poorly correlate with the variable load. We determine the set of wind and PV sites that best matches the load; we also show that the generation from any wind or PV site from the optimal set is positively correlated with the remaining variable load. The geographic distribution of optimal generation sites, e.g. North vs. South, shows features similar to phase transitions.
Acoustic Emission Test on Steel/Composite and Steel/Composite/Steel Built-Up Sections
Authors: Ghimire Rushie , Anderson Gary , Delfanian Fereidoon
Published: August 2012

Acoustic Emission (AE) has been widely used to monitor and inspect built-up steel/composite sections; primarily at the glue line. AE testing was conducted on steel-composite (SC) and steel-composite-steel (SCS) built-up sections to determine the glue line failure and damage sustained by the inner layer of the built-up section by putting the sensors on the inner and outer layers of the built-up sections. The straight specimens of steel/composite and steel/composite/steel were tested with load applied to only one steel layer. The AE sensors were placed on the outer steel component so that detected signals traveled through the loaded steel, glue lines, and the composite or the loaded steel component, two glue lines, composite and unloaded steel components of the built-up section(s). The AE signals received by the sensors placed on the loaded steel in tension was compared to signals of sensors placed directly opposite on the unloaded steel or composite to determine the effect the steel/composite and steel/composite/steel built-up sections had on the signal. AE signals were also compared to signals generated during tensile tests of steel specimens only and composite specimens only. AE parameters like amplitude, hits, counts, frequency, cumulative count, and rise time of the AE signals were recorded, analyzed, and compared. AE parameters were also compared to traditional material properties (like yield and failure stress and strain). Tested specimens were examined with a microscope and observations were compared and analyzed relative to AE and material parameters, and reported.
Quasi-Static and Dynamic Characterization of Oil-Based Modeling Clay and Numerical Simulation of Drop-Impact Test
Authors: Hernandez C. , Maranon A. , Ashcroft I. A. , Casas-Rodriguez J. P.
Published: August 2012

Numerical simulations require the determination of material constants associated to a given mathematical material model that accurately represents its mechanical behavior. Furthermore, for dynamic models, the characterization process should be accomplished at high strain rates since the mechanical properties of some materials are influenced by the rate of loading. This pressure-dependant behavior is commonly seen in paste-like materials such as oil-based modeling clay. This material, is widely used as simulating a material for analyzing metal forming processes, in impact applications as soft body impactor, or as backing material in ballistic resistance testing of body armors. There are many techniques used for characterizing these kinds of pastelike materials. Traditional quasi-static tests, such as compression or indentation, are the most commonly used, although, high strain rate techniques, such as the drop-impact test, are also used when dynamic properties are required. This paper presents the mechanical characterization of an oil-based modeling clay by two different techniques: quasi-static and a high strain rate technique. The results of a traditional quasi-static method, using compression tests, are compared with the constants determined by a proposed high strain rate characterization procedure that uses as input a single drop-impact test. Both sets of material constants are implemented in a numerical simulation that uses the power law plasticity material model. Drop impact numerical simulations and their verification against experimental results were performed to compare the accuracy of both sets of material constants and the suitability of the characterization techniques. Results illustrate that the proposed high strain rate characterization technique show advantages in the determination of the materials constants for the numerical simulation of dynamic events.
5 DOF Instrumented Master Device for Experimental Understanding of Intuitive Teleoperation
Authors: Diaz-Hernandez Octavio , Gonzalez-Villela Victor J.
Published: August 2012

Teleoperation it is a modern challenge within the areas of mechatronics, e.g. precision mechanics, control electronics, computational algorithms. Teleoperation arose from the necessity of handling nuclear material, but in recent years has come essential in others activities such as the space or undersea exploration, mobile robotics, medical applications and entertainment. The main goal in this work is to study the “operation at a distance,” with a master-slave system, to define the concept of “Intuitive Teleoperation,” like a novel approach to perform semiautonomous teleoperation, based on incomplete information from the environment, objects and system. In this level of the investigation the experimentation was realized with a 5 DOF anthropomorphic device (master device) that acquired data of the movements from a human operator, which was sent to a 5 DOF anthropomorphic robot (slave device). Both, direct kinematics (over the master device) and inverse kinematics (over the slave device) were used to calculate their space parameters (point coordinates, orientation) and to implement intuitive algorithms. Has been observed that the master device movements are followed and enhanced by the slave subsystem when the intuitive algorithms are activated. Semiautonomous teleoperation was achieved using a 5 DOF instrumented master device. The experiments enhanced the “operation at a distance” by defining an intuitive algorithm.
Engineering an Undergarment for Flash/Flame Protection
Authors: Hull Frazier , Gambill Jett , Hansche Andrew , Agni Gian , Evangelista John , Powell Celia , Auerbach Margaret , Dillon Joel , Arnas O¨zer
Published: August 2012

This paper presents a continuation of projects spanning the last two years. In year one, the physical characteristics and medical effects of burns and Improvised Explosive Device, IED, blasts were investigated [1]. In year two, the possible use of commercial intumescent materials with fabric was studied [2]. The identified needs for research into the effect of undergarments on burn protection are focused in this study. Additionally, Thermal Protective Performance, TPP-(ISO 17492) and Air Permeability, AP-(ASTM D737) tests were performed to gather the data needed for the analysis of flame and thermal resistance as well as comfort and breathability. Out of the seven samples evaluated, the Sample D, composed of 94% m-aramid, 5% p-aramid and 1% static dissipative fiber, shirt had the best overall performance in terms of air permeability, average TPP rating, and time to second degree burn. Another finding was that polyester undershirts may be dangerous in the event of a flash fire situation because the fabric could melt and stick to the Soldier’s skin causing more severe burn injury. Additionally, an initial framework for a basic mathematical model representing the system was created. This model can be further refined to yield more accurate results and eventually be used to help predict the material properties required in fabrics to design a more protective undergarment.
Numerical Study of Microchamber Filling in Centrifugal Microfluidics
Authors: Niedbalski Nick , Kang Seok-Won , Banerjee Debjyoti
Published: August 2012

Numerical investigation of the transient, coupled hydrodynamic and thermal behavior of a novel polymerase chain reaction (PCR) centrifugal microfluidic system is presented in this study. The driving mechanism for flow within these devices is modeled as a combination of the capillary forces and rotationally induced pressure gradient working in opposition to viscous forces, which are functions of rotation speed and fluid properties. The physical properties of the working fluid are in turn functions of temperature, some of which can have significant variations over the operating temperature ranges of a PCR thermal cycle. The complex balance of viscous, capillary, and rotationally induced inertial forces are crucial factors in optimizing the design of such devices. Hence, the effects of temperature variation on the filling performance cannot be neglected. A commercial CFD code is utilized to simulate the filling of a microchamber when subjected to thermal conditions typical of a PCR thermal cycle. The numerical model accounts for the temperature dependence of the working fluid’s viscosity and surface tension by simultaneously solving the Navier-Stokes and energy equations. The free surface morphology (position, shape) and total chamber fill fraction as a function of time is predicted by using the volume of fluids (VOF) method. Comparison of the predictions from the temperature dependent numerical model to that which assume said physical properties to be constant, demonstrates the strong effect of the fluid’s viscosity and surface tension on the filling rate for various rotation speeds.
Energy Harvesting From Vertical Deflection of Railroad Track Using a Hydraulic System for Improving Railroad Track Safety
Authors: Nelson Carl A. , Pourghodrat Abolfazl , Fateh Mahmood
Published: August 2012

Grade crossings are locations of significant interest for prevention of collisions, injuries and fatalities in the railroad transportation system. Another area of concern is track maintenance, since derailments resulting from mechanically deficient track structures can cause significant endangerment to property and lives. A commonality between these two classes of incidents is that many occur in remote areas due to the lack of electrical infrastructure to power automated warning systems and/or track health monitoring sensor networks. Providing electrical infrastructure to railroad crossings in remote areas is often not economical, and other alternative sources of electricity such as solar and wind energy are not reliable and robust. This motivated development of a hydraulic system capable of harnessing power from vertical deflection of railroad track due to passing railcar traffic. A hydraulic cylinder mounted under the bottom of the rail is compressed and relaxed by passage of each railcar, forcing the hydraulic fluid towards a hydraulic motor and converting the hydraulic pressure and flow into rotational motion and torque. The rotational motion is amplified to drive a PMDC generator. The hydraulic system was developed and testing was performed to verify the functionality of the hydraulic system and quantify the power output.
Comparison Study of Active Noise Cancelation Algorithms for Impulsive Noise
Authors: Li Peng , Yu Xun
Published: August 2012

Control of impulsive noise is one important challenge for the practical implementation of active noise control (ANC) systems. The advantages and disadvantages of popular filtered-X least mean square (FXLMS) ANC algorithm and nonlinear filtered-X least mean M-estimate (FXLMM) algorithm are discussed in this paper. A new modified FXLMM algorithm is also proposed to achieve better performance in controlling impulsive noise. Computer simulations are carried out for all the three algorithms and the results are presented and analyzed. The results show that the FXLMM and modified FXLMM algorithms are more robust in suppressing the adverse effect of sudden large amplitude impulses than FXLMS algorithm. In particular, the proposed modified FXLMM algorithm can achieve better stability without sacrificing the performance of residual noise when encountering impulses.
Measuring Ignition Temperature and the Rate of Energy Generation From Canola Methyl Ester and Soy Methyl Ester in Oxygen-Nitrogen Mixtures on Platinum-Rhodium
Authors: McGary Bradley , Steciak Judi , Budwig Ralph , Beyerlein Steve
Published: August 2012

A heated plug flow reactor was used to study the reactions of nonflammable mixtures of canola methyl ester-oxygen and soybean methyl ester-oxygen diluted with nitrogen over a coiled 90%:10% platinum:rhodium wire catalyst. The temperature the catalyst needed to reach to initiate surface reactions (ignition temperature) and the subsequent rate of energy generation were determined. The absolute volume fraction of fuel was varied from 0.238% to 0.445% and the relative fuel-oxygen equivalence ratio, φ, was varied between 0.4 and 1.0. The 127 micrometer diameter Pt-Rh wire was coiled and suspended crosswise in the quartz tube of the reactor. Evaporated biodiesel was delivered by heated nitrogen into the apparatus and blended with oxygen in a mixing nozzle. The wire catalyst was electrically heated and acted as a resistance thermometer to measure its average temperature. Ignition temperatures increased with increasing equivalence ratio and volumetric fuel vapor percentage, thus indicating initial fuel coverage of the catalyst surface. Temperatures as low as 912 K at φ = 0.4 for 0.268% Soy Methyl Ester (SME) and as high as 991 K at φ = 1.0 for 0.445% Canola Methyl Ester (CME) were recorded. The rate of energy generated due to surface reactions for both biodiesels decreased with increasing equivalence ratio and generated less energy as fuel percentages decreased. The lowest and highest rates of energy generation were both obtained from experiments with CME with 6.9 W/cm2 at φ = 1 for 0.268% fuel and 25.3 W/cm2 at φ = 0.4 for 0.445% fuel. The extremes of the rate of heat generated from SME reactions were 5.1 W/cm2 and 28.6 W/cm2, both at φ = 0.4, with 0.238% and 0.417% fuel, respectively. Another outcome of this work was achieving steady evaporation of microliter/hour heavy fuel vapor flow rates. This was aided by thermogravimetric analysis (TGA) to determine thin-film vaporization temperatures. CME and SME had the lowest evaporation temperatures of 188 K and 186 K, respectively.
Effect of Brownian Motion and External Magnetic Field on the Effective Heat Capacity of Ferrofluids
Authors: Mousavi Kh. Narges Susan , Kumar Sunil , Narayanaswamy Arvind
Published: August 2012

An Eulerian formalism is used to derive the energy equation for a system of magnetic nanoparticles in a fluid (ferrofluid) in the presence of uniform magnetic field. The energy equation proposed here contains an effective heat capacity, which has contributions from: (1) Brownian motion of nanoparticles, (2) magnetic field, (3) temperature, and (4) volume fraction of particles. The modified term quantitatively shows the negligible contribution of the first three factors but the significant effect of concentration of particles in change in heat capacity of ferrofluid. In order to have a better understanding of the problem, the equation is converted to a non dimensional form from which the role of each of physical parameters can be inferred.
Teaching Formulation Skills in an Upper Level Fluid Mechanics Course
Authors: Ghosh Amitabha
Published: August 2012

This paper represents an instructional experience to teach formulation skills to upper level students in the thermal-fluids concentration area following a synthesizing and reinforcing approach. Common deficiencies in student performance are discussed and linked to the background context. This work establishes a systematic feedback loop for instructors teaching lower level courses and provides guidelines for the graduate emphasis. Examples are presented from a collection of four upper level courses in Fluid Mechanics. The paper also furnishes motivational techniques, observations, results and comments that can strengthen future administration of this approach.
Water and Greenhouse Gas Tradeoffs Associated With a Transition to a Low Carbon Transportation System
Authors: Dodder Rebecca , Felgenhauer Tyler , Yelverton William , King Carey
Published: August 2012

Transportation fuels are heavily dominated by the use of petroleum, but concerns over oil depletion (e.g., peak oil), energy security, and greenhouse gas emissions from petroleum combustion are driving the search for alternatives. As we look to shift away from petroleum-based transportation fuels, most options consume and withdraw more water during their life cycle. Thus, shifting to alternative fuel and energy supplies for transportation will likely increase water use for the transportation sector. Previous work suggests that water consumption for transportation could reach 10% of total U.S. water consumption when meeting the Federal Renewable Fuels Standard mandate at modest irrigation levels for feedstock crops (corn, cellulosic grasses) in combination with other alternative fuels and vehicle technologies (electric vehicles, natural gas vehicles, etc.), but more refined analysis is needed. It is important to understand when and where these new water demands for transportation are anticipated to occur. This paper presents results from simulations of the U.S. 9-region (EPAUS9r) MARKAL (MARKet ALlocation) integrated energy systems model for mapping the changes in water withdrawal and consumption during a transition to a low carbon-emitting U.S. transportation fleet. The advantage of using a bottom-up, multi-sector model like MARKAL is the ability to look at consistent scenarios for the full energy system, and endogenously capture interactions between different sectors (e.g. electric power production, biorefineries, and the LDV fleet). MARKAL can simulate a baseline scenario driven by assumptions for biomass feedstock and fossil resource costs and availability, as well as the costs of converting those resources to liquid fuels and electricity. We investigate alternative scenarios both with and without carbon constraints, while varying the pace of vehicle electrification. We compare these scenarios to assess regional differences in water needs as well as aggregate water demand for transportation energy, and how those trade off against greenhouse gas emissions reductions. Our results indicate that the regional water demands and interregional transfers of embodied water could be significant as the light-duty vehicle fleet moves away from petroleum-based fuels, with exports of embodied water on the order of hundreds of billion gallons of water per year for ethanol coming from the Midwest. Interregional transfers of water embodied in electricity may also reach tens of billion gallons of water per year. However, these water requirements will vary substantially based on the light-duty vehicle mix, carbon policy, electric power generation mix, biofuel production levels, and feedstock characteristics.
Pool Boiling Heat Transfer Characteristics of HFO-1234yf With and Without Microporous-Enhanced Surfaces
Authors: Moreno Gilberto , Narumanchi Sreekant , King Charles
Published: August 2012

This fundamental study characterizes the pool boiling performance of a new refrigerant, HFO-1234yf (hydrofluoroolefin 2,3,3,3-tetrafluoropropene). The similarities in thermophysical properties with HFC-134a and low global warming potential make HFO-1234yf the prospective next generation refrigerant in automotive air-conditioning systems. This study examines the possibility of using this refrigerant for two-phase cooling of hybrid and electric vehicle power electronic components. Pool boiling experiments were conducted with HFO-1234yf and HFC-134a at system pressures ranging from 0.7 to 1.7 MPa using horizontally oriented 1 cm2 heat sources. Results show that the boiling heat transfer coefficients of HFO-1234yf and HFC-134a are nearly identical at lower heat fluxes. HFO-1234yf yielded lower heat transfer coefficients at higher heat fluxes and lower critical heat flux (CHF) as compared with HFC-134a. To enhance boiling heat transfer, a copper microporous coating was applied to the test surfaces. The coating provided enhancement to both the boiling heat transfer coefficients and CHF, for both refrigerants, at all tested pressures. Increasing pressure decreases the level of heat transfer coefficient enhancements while increasing the level of CHF enhancements.
Four-Fin Bio-Inspired UUV: Modeling and Control Solutions
Authors: Geder Jason D. , Ramamurti Ravi , Palmisano John , Pruessner Marius , Ratna Banahalli , Sandberg William C.
Published: August 2012

This paper describes the modeling and control development of a bio-inspired unmanned underwater vehicle (UUV) propelled by four pectoral fins. Based on both computational fluid dynamics (CFD) and experimental fin data, we develop a UUV model that focuses on an accurate representation of the fin-generated forces. Models of these forces span a range of controllable fin parameters, as well as take into account leading-trailing fin interactions and free stream flow speeds. The vehicle model is validated by comparing open-loop simulated responses with experimentally measured responses to identical fin inputs. Closed-loop control algorithms, which command changes in fin kinematics, are tested on the vehicle. Comparison of experimental and simulation results for various maneuvers validates the fin and vehicle models, and demonstrates the precise maneuvering capabilities enabled by the actively controlled curvature pectoral fins.
Modeling Heart Rate Baroreflex Mechanism and its Application in Predicting Acute Hypotensive Episodes
Authors: Jalali Ali , Nataraj C.
Published: August 2012

In this paper a new nonlinear system identification approach is developed for identification of the heart rate (HR) baroreflex mechanism. The developed model in then used in the task of acute hypotensive episodes (AHE) prediction. The AHE is defined as any period of 30 min or more during which at least 90% of the mean arterial pressure (MAP) measurements are below 60 mmHg. The proposed HR baroreflex model is based on inherent features of the autonomic nervous system for which we develop an adaptive neuro-fuzzy inference system (ANFIS) structure. The model showed significant improvement in HR prediction accuracy in terms of the normalized root mean square error (NRMSE) in comparison with previously reported results. We achieved a value of 0.191 in mean NRMSE in prediction of HR in this paper which is about 20% better than the best reported result in other papers. For the task of AHE prediction, since arterial pressure has a direct correlation with heart rate, we could simply find the periods in which HR drops blow a certain level without losing generality. The demonstrated AHE data for twenty patients are selected to validate the proposed algorithm. Results show that the proposed method could truly predict occurrence of the AHE in 9 out of the 10 cases analyzed. Results show reliable accuracy in predicting AHE in these patients.
Cold Pre-Compression Treatment of Gas Diffusion Electrode for PEM Fuel Cells
Authors: Jia Shan , Liu Hongtan
Published: August 2012

In a PEM fuel cell, it has been shown that the compression under the land area is the main reason for the observed higher performance than that under channel areas. If the area under the channel can also benefit from such a compression the overall performance of the cell will increase. Since the areas under the channel are not directly compressed in an assembled fuel cell, it is the objective of this study to determine if a cold pre-compression treatment of the gas diffusion electrode (GDE) may have a significant positive effect on the overall performance of the cell. First, the GDE is cold pre-compressed to a level similar to the compression that would be experienced by the land areas in an assembled fuel cell. Then the pre-compressed GDE is assembled in a regular test fuel cell and the performances under various operating conditions are studied. Finally, the cell performance results are compared with the results obtained from a fuel cell with a regular GDE. The experimental results show that cold pre-compress of the GDE has significantly improved the overall performance of the fuel cell. Further experiments have also been conducted with five different levels of cold pre-compression to determine if there exists an optimal compression and its value if it exists. The experimental results show that the performance of the fuel cell first increases with the level of cold pre-compression, reaching a maximum and then decreases with the level of compression. These results clearly indicate that there indeed exists an optimal level of compression. Further studies using both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) have further corroborated the cell performance findings as well as the underlying mechanism. The results of EIS indicate that the ohmic resistance is hardly affected by the cold pre-compression, while the charge transfer resistance is significantly affected, especially in high current density region. The CV results show that the electro-chemical area (ECA) is higher with the cold pre-compressed GDE and there is an optimal compression that results in the maximum ECA. Therefore, the experimental results have shown that (a) the cold pre-compression treatment of the GDE is an effective and simple technique to increase PEM fuel cell performances; (b) there exists an optimal compression level at which the cell reaches its maximum performance; and (c) the increased performance is due to the increase of ECA resulting from the cold pre-compression treatment.
Development of a New Finite Element Model in Abaqus for the WorldSID 50th Percentile Male Side Impact Dummy
Authors: Scarlat George , Sankar Sridhar , Oancea Victor , Grimes Bill
Published: August 2012

This paper describes the modeling and validation of the new WorldSID 50th percentile male dummy (WorldSID50) model for the Abaqus finite element (FE) software suite [1]. The Abaqus WorldSID50 model has been developed by Dassault Syste`mes Simulia Corp. in cooperation with the Partnership for Dummy Technology and Biomechanics (PDB), a consortium that includes the following German automobile manufacturers: Audi, BMW, Daimler, Porsche, and Volkswagen. The objective of the dummy development project was to develop a robust virtual dummy model that closely mimics the behavior of the hardware dummy in order to minimize the need for physical testing during vehicle design. Data obtained through extensive experimental tests performed at all levels of the dummy assembly — material coupon, component, sub-assembly, and full dummy — were used to calibrate and validate the finite element model. The Abaqus WorldSID50 model results show good correlation with the hardware dummy output signals for a wide range of tests. The Abaqus WorldSID50 model was approved for use in production by the PDB.
Size Reduction of Cellulosic Biomass in Biofuel Manufacturing: Effects of Biomass Crystallinity and Particle Size
Authors: Zhang Meng , Song Xiaoxu , Zhang P. F. , Pei Z. J. , Deines T.
Published: August 2012

Gradual depletion of world petroleum reserves and increasing environmental impact of greenhouse gas emissions make it urgent to develop sustainable alternatives to petroleum-based transportation fuels. Cellulosic biofuels provide one such alternative in the short to medium term. In order to convert cellulosic biomass into biofuels, size reduction is a necessary step. In the literature, there are inconsistent reports about the effects of particle size and biomass crystallinity on sugar yield (proportional to biofuel yield). An important reason for this inconsistence is that particle formation in current size reduction methods is not well controlled, causing the effects of these two variables confounded. This paper presents an experimental study on size reduction of poplar wood using a lathe, where particle formation could be well controlled to prevent the effects of these two variables from being confounded. In this study, particle size was controlled by different numbers of slots cut on the workpiece. Particles with the same crystallinity but different particle sizes were produced. This will make it possible to study the effects of particle size on biofuel yield independently, and reveal future research opportunities to understand the effects of size reduction in cellulosic biofuel manufacturing.
Design and Validation of a Particulate Matter Management System Computationally
Authors: Peymani F. Yoosef , Ghanbari Arash S. , Liu Yucheng , Hayatdavoudi Asad
Published: August 2012

A cost effective and efficient technology was developed to cleanly remove particulate and fibrous matter from a container while avoiding dispersing the particles in the environment. This paper presents the whole process of computationally developing and validating a system which works based on medium and particles characteristics and can efficiently remove particles in the size range of 5–1000μm from the container. In the presented system a viscous medium was designed to capture and flocculate the particulate matter. One of the factors which will lower the operating costs is that the viscous medium can be easily recycled and the flocculated particles with minimal volume can be disposed of safely. ANSYS FLUENT package was used to simulate our proposed design. The effects of various container geometry, particle size, particle specific gravity, and pressure-velocity boundary conditions on separation efficiency of the design have been studied by using different multiphase models along with viscous and discreet phase models. The result of simulation work led to develop the optimum design, find the maximum and minimum particle size and particulate specific gravity which can be separated while considering the effect of gravity on separation efficiency. Finally the maximum loading capacity of model was determined in a way that particles dispersion into environment was avoided.
A Robotic Exoskeleton Device for Augmenting Wrist Movement and Grip Function in Debilitated Patients
Authors: Gilman Chad V. , Ben-Tzvi Pinhas , Yessin Gabriel , Danoff Jerome
Published: August 2012

Many diseases and conditions can cause reduced motor function in joints throughout the body. This paper identifies such health issues that affect the function of the wrist and hand in particular. After identifying these conditions, a concept three degree of freedom (two DOFs of the wrist plus cylindrical grip) robotic exoskeleton design is presented that is intended to augment a patient’s remaining function and strength while remaining portable and lightweight. With this in mind, the device is intended to allow a patient to use and operate it independently, without the presence of a therapist. The mechanical design of the exoskeleton is described in depth, along with details of potential actuation methods. The main idea for control of the device is to detect small torque values as a patient attempts a movement and in turn predict what the intended outcome would be if the patient were at full strength. After processing this information the robot would assist the patient in facilitating the anticipated movement. This is in contrast to alternate control methods, which rely primarily on electromyography (EMG) to detect signals to muscles that control certain movements. Electromyography can be unreliable because many of the conditions that cause debilitated function also cause an interruption or break in these signals.
Multi-Frequency Focused Ultrasound for Tissue Ablation
Authors: Bakshi Saurabh , Guo Sijia , Jiang Xiaoning
Published: August 2012

In this study, the effectiveness of tissue ablation was investigated using multi-frequency high intensity focused ultrasound (HIFU) transducers (950 kHz, 1.5 MHz). Temperature rise and lesion volume were recorded when chicken tissue was ablated by focused ultrasound (FUS) with controlled ultrasound power and exposure time using single frequency and multi-frequency modes. It was found that multi-frequency tissue ablation gives a higher maximum temperature accompanied by a faster rise, and a larger ablation lesion volume, compared with single frequency ablation, under the same input conditions of electrical power, exposure time and depth of focus. Also, it was concluded that the same desired tissue temperature and ablation lesion conditions can be attained by using less power for the multi-frequency ablation. These findings are promising because the multi-frequency ultrasound ablation using FUS with a greater frequency difference could result in promising imaging guided effective therapy using one multi-frequency probe.
Bayesian Updating of Deteriorating Bridge Infrastructures Through Monitoring Data
Authors: Taflanidis Alexandros , Gidaris Ioannis
Published: August 2012

The knowledge about the deteriorating characteristics and future operation conditions in civil infrastructure systems is never complete. Any decision-making framework must include a rational approach for quantifying these uncertainties and their bearing on the decision making process, thought the entire life-cycle of operation. A probability logic approach provides a consistent foundation for this, employing probability models to characterize the relative likelihood of the different system properties. Health monitoring data, when available, may be used to update the probabilistic quantification related to these uncertainties as well the future assessment of the condition of the infrastructure system under consideration. This work presents a Bayesian framework for updating the assessment of bridge infrastructure systems through use of monitoring data. Focus is put on deteriorating characteristics for bridges, which can have a significant impact on the reliability of the system. Stochastic simulation techniques, primarily based on Markov Chain Monte Carlo simulation, are proposed for the Bayesian updating and various models classes are examined for the bridge system. The updating of the relative likelihood for each of the models through monitoring data is also considered. An illustrative example is presented that demonstrates the power of this approach for updating the assessment of an aging overpass concrete bridge and guiding maintenance decisions.