liquid spray fuel injection studies using direct numerical simulation …€¦ · ·...

MCEN 5208 Fall 2010 Potential Research Projects

Last updated: 9/29/2010 1

LiquidSprayFuelInjectionStudiesusingDirectNumericalSimulation(DNS)Student: Ji Peng

Advisor: Olivier Desjardins Co-advisor: John Daily

Most energy conversion devices today burn fuel that is stored in liquid form. However, combustion takes place in the gas phase, meaning that the liquid has to be evaporated before it can burn. Therefore, to maximize efficiency, the fuel is first atomized into a fine spray. Because of the complexity of the physics behind liquid atomization, the current modeling paradigm is to rely on phenomenological models that require fine-tuning with the aid of experimental data. As a consequence, these over-simplified models are not predictive, and this limitation currently represents one of the main hurdles in advanced computational modeling of combustion engines. Therefore, there is a need for new atomization models based on first principles that capture the complex physical processes associated with turbulent liquid break-up and accurately predict spray droplet size and velocity distributions. Toward this goal, this project aims at conducting Direct Numerical Simulation (DNS) of turbulent atomization in order to understand in more details the physics of atomization. This DNS study will be complemented by the experimental work described in the previous project. Expected accomplishments:

1. Extensive review of literature on multiphase flow modeling. 2. Familiarization with an advanced research code and high performance computing environment. 3. Simulation of several injectors under various flow conditions. 4. Close collaboration with _rst project aiming at experimentally investigating these flows. 5. Develop strategies for comparing experimental measurements and simulations.

Figure 2: DNS of Diesel fuel injection on 1.2 billion grid points.



Micro‐PatternedTreadsforInvivoMobilityStudent: Levin Sliker

Advisor: Mark Rentschler The focus of this project is on the design, fabrication and testing of prototype micro-patterned treads that will enable in vivo mobility on any number of different tissues. This project will require fabrication techniques using photolithography for tread creation, experimental testing of various tread design in the lab on a benchtop system using tissue analogs and tissues, numerical and analytical modeling of the contact mechanics involved at the tread-tissue interface, and experimental testing of candidate designs during animal surgery. The expectation is that sufficient experimental data is collected and contact mechanics models are established so that a quality journal paper can be submitted for publication review by the end of the spring semester.

Applying Ultraviolet Energy to Ventilation Systems for decreasing Disease Transmission and Energy Use

Student: Julia Luongo Advisor: Shelly Miller

The use of Ultraviolet Energy (UV) within an HVAC system is growing rapidly. In one application, high levels of UV energy are installed in the HVAC ducting for disinfection of microbes in moving air streams. In another very popular application and the subject for this research request, UV energy is applied to the air conditioning coil and drain pan to prohibit microbial growth (bacteria and mold) from fouling the coil and drain pan. This application is reported to reduce maintenance costs, reduce pressure drop across the evaporator coils, and improve heat transfer of evaporator coils, therefore resulting in overall energy savings. The energy savings are also a result of improved air flow and reduction in required air handler (fan) energy. In additions to these changes the use of UV on air conditioning coils has been demonstrated to improve the indoor air quality and result in indirect savings such as improved employee or student attendance, reduction of complaints and reduction of respiratory illness. The goal of the proposed research is to demonstrate in a laboratory setting that UV technology can contribute to energy savings. A small-scale reactor will be built for the experiments and will consist of a dedicated air handling unit, ducting and UV lamps on cooling coils. Laboratory skills are needed for this research project, including microbiology and mechanical systems.

MechanicsandPhysicsofLi‐ionBatteriesStudent: Evan Anderson

Advisor: Marty Dunn

Rechargeable lithium ion batteries play a central role in today’s increasingly mobile society, with notable prominence in the portable computing, telecommunications, and entertainment industries. Their attractiveness, as compared to other rechargeable batteries, arises from their higher energy density (both gravimetric and volumetric), higher operating voltage, lower self-discharge rate, and the lack of memory effects. Further applications, though, are pushing for increases in energy density and mass capacity. This can be enabled by advances in the specific energy capacity of electrode materials. For example,



significant effort is ongoing to replace carbonaceous anodes with higher capacity materials. The most attractive candidate appears to be silicon which has the highest known capacity. A drawback with Silicon is that an enormous volume expansion occurs upon Li insertion and stresses associated with these large volume changes have been cited as the cause of cracking and pulverization of Si electrodes that leads to loss of electrical contact and eventual capacity fade during Li insertion-extraction cycling. Mechanistic details regarding the cyclic degradation that leads to capacity fade, though, seem to be lacking.

Over the last few years we have developed a multiscale computational architecture to simulate the complex operation of Li-ion batteries. The approach consists of a multiscale framework incorporating battery-level models, microstructural models of heterogeneous electrodes, and micro/nanoscale models of the electrode constituents. At all scales these models incorporate fully coupled diffusion, mechanics, and electrochemical reaction kinetics. There are a number of possible Introduction to Research projects that can be pursued and can then fit into this overall architecture to richen our modeling and simulation capabilities. These include:

1. Growth and Evolution of the Solid-Electrolyte Interface (SEI) layer: we will extend our micro-scale models to include the initiation and growth of an SEI layer during Li cycling.

2. Finite Deformation of Electrode Constituents: to date all of our models involve infinitesimal deformations. Here we will extend them to include finite deformation so that the are directly applicable to cases like Silicon which undergoes volume changes of 300% or so.

3. Thermodynamics of Li Insertion and Mechanics: the goal here is to cast our understanding and models into a rigorous thermodynamics framework.

4. Fracture Mechanics Analysis of Li Insertion: here we will build on our coupled reaction/diffusion/stress models of spherical particles to analyze particle fracture and damage from a fracture mechanics perspective. This entails analyzing particles with small cracks during Li insertion and extraction.

5. Other interesting problems in this area exist and can be the subject of an Introduction to Research project.

SolarCollectorEfficiencyandAirQualityStudent: Liza Boyle Advisor: Hannigan

Motivation and Background. Researchers at NREL who have been evaluating concentrated solar power (CSP) expressed great concern about collector efficiency losses caused by deposition of airborne particulate matter (PM). They have found that the performance of a solar reflector dropped by 8-12% between their 8-day cleanings. This degradation of solar collector performance is seen for solar photovoltaic and solar thermal hot water installations as well. These large efficiency losses make all solar power technologies a less affordable alternative and the lack of predictability of the affect makes the already difficult problem of grid integration even more troublesome. Understanding the details of the PM deposition effect and developing mitigation strategies is crucial to the future success of all solar energy harvesting technologies. To develop mitigation strategies, it is essential that we be able to link PM emissions to airborne concentrations then to deposition on solar collectors and finally to the impact on solar radiation transmission given the PM deposition. At present, there is very limited information on deposition processes for PM onto solar collectors and only simplistic attempts to develop relationships between the deposited PM and the collector efficiency.



Objectives. The specific objective of this project is to undertake a systematic measurement campaign that will enable us to develop models for the two critical processes: (1) a model capable of calculating the airborne PM deposition to solar collector surface as a function of particle size and surface orientation, and (2) solar radiation transmission reductions as a function of deposited PM loads by size and chemical character. The proposed measurement campaign will leverage extensive existing PM characterizations efforts in the Front Range as well as the world’s best solar radiation measurements facility, located at NREL’s Solar Radiation and Research Laboratory.

UnderstandingtheSpatialVariabilityofSourcesofPM2.5inDenverStudent: Mingjie Xie Advisor: Hannigan

Motivation and Background. The Denver Aerosol Sources and Health (DASH) study began in mid-2004 with the objective to identify the sources of ambient air pollution that contribute to the health effects of short-term exposure to fine particulate matter (PM2.5). Interim analysis using PM2.5 chemical composition data based on an ongoing intensive monitoring and chemical speciation effort that has been underway since mid-2002 indicated that traffic-associated emissions, in particular diesel emissions as reflected by elemental carbon (EC), was more strongly associated with increased daily total and cardio-respiratory mortality than either total PM2.5 mass or other PM components. Preliminary analyses performed in preparing the original study proposal suggested that daily concentrations of a limited number of PM components were reasonably spatially homogenous in Denver. Since the study began, new information for other US cities (Atlanta, New York City and St. Louis) calls this impression into question, as some PM component and source concentrations appear spatially heterogeneous.

Objectives. The primary objective for this project is to gather information to determine whether the use of a single residential (population-oriented) monitoring site as currently used adequately reflects short-term temporal variability in sources over space in the Denver metropolitan area. The extent of this spatial-temporal variability will affect the interpretation of PM component and source health effect estimates currently being generated by the DASH health studies. To address this, we have collected one year of supplemental PM component monitoring in areas selected to reflect spatial variation in PM components that correspond to large portions of the Denver population. This project will use the collected spatial samples to undertake organic compound quantification via gas chromatography/mass spectrometry followed by source apportionment using those organic compounds. Then, the student performing this project will write a journal manuscript that describes the spatial variability of PM2.5 sources in Denver.

DevelopingDataAnalysisToolsforMetalOxideSensorsDeployedasPersonalVOCExposureMonitors

Student: Zhifu Pei Advisor: Hannigan

Motivation: Over the past two years, several inexpensive and miniaturized, ~ 1 cm scale, volatile organic compound (VOC) sensors have reached the commercial market. These sensors are typically used for industrial applications which involve relatively high VOC concentrations. At the same time,



public health researchers exploring the adverse health impacts of air pollutants on large populations have reached a point where there is a critical need to improve the exposure assessment portion of their analysis, moving from a few monitors in an urban area to numerous individual/personal monitors. As such, there exists an exciting opportunity to develop tools that allow public health researchers to understand air pollutant exposure at the personal scale. A research team that includes Professors Hannigan (ME), Shang (ECEE), and Lv (CS) has already moved on this idea. One challenge faced by this team is sensor data processing under non-ideal sensor conditions at relatively lower concentrations.

Project Objective: Develop tools that can be used for real-time optimization of power cycling for the VOC sensors where optimization includes capture of significant VOC exposures, exposure changes and maximizes time between battery charging (in other words, minimizes energy use). A significant piece to that effort will involve improving our understanding of sensor signal processing at non-steady state. At present, we have observed two non-steady state problems. First, the metal oxide sensors have a relatively long warm-up time (~30 to 60 minutes); during this time, the voltage reading slowly grows for a sensor held in a constant concentration environment. This growth in signal is approximately logarithmic and reaches a maximum in ~ 30 to 60 minutes depending on individual sensor and the final concentration; we term this maximum ‘steady state’. When we cycle sensor power on the minute scale, which is more appropriate for keeping track of VOC exposure and exposure changes, the sensor is never at steady state. The second non-steady state problem is sensor hysteresis; when the sensor experiences a relatively high concentration of VOCs and is then moved to a relatively clean environment with low concentrations, there is a time lag until the sensor reaches steady state. The amount of signal hysteresis is likely a function of the change in concentration and time although we have not explored this in depth. A further complication is that hysteresis will be difficult to assess completely during power cycling. There is potential to add real-time dynamic power cycling that improves understanding of hysteresis and thus measurement data quality while still seeking minimal sensor energy use. The student working on this project will be using an existing sensor calibration chamber and developing data analysis software. The student will be working with a team of students from mechanical, electrical and computer science. The student will need to complete a draft manuscript for a scientific journal to successfully complete this project.

Project:LaserUltrasonicsinOpticallyTransparentMediaStudent: Jake Dove

Advisor: Todd Murray Laser based ultrasonics is used for a wide range of materials characterization applications, including the detection of small scale subsurface defects in microelectronics, the rapid inspection of composite materials used in the aerospace industry, and the optomechanical operation of micro- and nanoscale devices. In this technique, pulsed or continuous wave lasers are used to excite elastic waves or vibrations in materials which are subsequently detected using, for example, optical interferometry or optical beam deflection. The majority of the work in laser ultrasonics to date has used the photothermal effect for elastic wave generation, where light absorption at the sample surface leads to local heating, and the resulting thermal expansion serves to launch elastic waves. In addition to the photothermal effect, light can produce surface deformation through, for example, photon radiation pressure and electrostriction. In



this project, we propose to study the surface deformation produced by light in optically transparent or highly reflective materials, where photon radiation pressure may dominate over other deformation mechanisms. Photon radiation pressure may offer the possibility of locally pushing on the surface of materials in a highly controlled manner. This project will involve simulation of the transient elastic field generated by photon radiation pressure, as well as quantitative measurements of the surface displacement produced by high intensity laser pulses in select materials. Applications of the proposed “optical indentation” technique include the quantitative measurement of near-surface mechanical properties, and local mechanical characterization of polymers and gels.

YourOwnUndergraduateResearchExperienceattheUniversityofColorado:YOU’RE@CU

Student: Janet Tsai Advisors: Daria Kotys-Schwartz and Ginger Ferguson

YOU’RE@CU: a new program designed to link graduates with 1st and 2nd year undergraduates through Engineering research projects and to support undergraduate STEM education. This program will be formed by Dr. Ginger Ferguson in collaboration with Dr. Beverly Louie and the CU Broadening Opportunity through Leadership and Diversity (BOLD) Center with the aims of: improving retention of diverse groups in Engineering from the start of their college careers, encouraging vertical integration of learning, and providing a hands-on training opportunity for graduate students to gain mentoring skills. YOU’RE@CU will fill a gap at CU-Boulder by serving the needs of our minority students. It is anticipated that this program will improve recruitment of minorities and women to engineering through outreach to local high schools with high minority populations; retention will be improved through creation of a community that bridges the gap between undergraduate and graduate students, engaging underclassmen by providing a unique glimpse of cutting-edge areas in bioengineering. YOU’RE @ CU will provide unique access to research opportunities four our diverse population – many of whom working during the semester. YOU’RE@CU will provide course credit in exchange for participation and a relatively low time commitment as compared to other undergraduate research programs, thus the working student can more readily gain research experience in YOU’RE@CU. Graduate students need mentoring experience, yet most lack and formal mentoring training. Our program seeks to address this deficiency and to provide an additional resource in the form of a seminar, open to all engineering graduate students, which will focus on career development and work‐life balance. We seek for YOU’RE@CU to formalize mentoring training in a supportive environment that provides unique yet highly valuable resources for our graduate students. This research project will examine undergraduate and graduate attitudinal reactions to YOU’RE@CU, and add to the body of knowledge in two research areas identified by the Engineering Education Research Colloquies as priority research initiatives in engineering education: engineering learning systems and engineering diversity and inclusiveness. For this project a mechanical engineering student will work with the YOU’RE@CU project team to:

• Understand quantitative and qualitative methods in engineering education research • Understand the theoretical framework of student mentoring and research lab experiences (e.g., situated

learning theory, socialization theory, college student retention theory)• Develop research questions • Develop and submit HRC approval for the project



• Identify validated surveys, as well as develop and test surveys to gather quantitative and qualitative data to assess the impact of YOU’RE@CU

• Conduct experimental focus group interviews with undergraduate students and graduate students • Perform data analysis using current statistical approaches

Mechanicalandmaterialpropertychangesinbonewithexperimentaldiabetes

Student: Kayla Maranjian Faculty Advisor: Virginia Ferguson

The focus of this project is to understand the biomechanical and concomitant material property / composition alterations that occur in bone with diabetes. In this project, bones will be collected and analyzed from mice that have been treated with streptozotocin to experimentally induce a diabetic state. Mechanical testing in three-point bending will be used to assess strength, stiffness, and other relevant gross mechanical properties; nanoindentation will be used to assess local material properties; and composition will be assessed by both ashing bones and also by quantifying mineral content using backscattered electron microscopy. Data will be correlated with information on the degree of collagen cross-linking in bones from these same mice (collected by a UC Denver collaborator). The student will perform a full literature review. This project will culminate in a draft manuscript by the end of this fall semester.

TheEffectofMonetizingExternalitiesStudent: Kristen Brown

Co-Advisors: Jana Milford & Daven Henze This project will examine how the US electricity generation mix might change over the coming decades if damage costs from conventional air pollution and greenhouse gas emissions were to be “internalized” through emissions fees or taxes. The study will utilize the EPA-MARKAL (MARket ALlocation) model which describes the current and projected US energy system from 2000 to 2050. Existing and prospective energy resources and emissions control technologies will be included. Marginal damage costs will be computed from the National Research Council’s 2009 estimates for conventional air pollutants, and a range of published external cost estimates will be considered for greenhouse gas damages. Life cycle impacts of power generation will be taken into account in these damage costs. The effect of both uniform and regionally differentiated taxes will be explored. The model’s sensitivity to the timing and duration of such taxes and the predicted costs and demand will also be investigated.

Templating“BreathFigures”byTopographicandChemicalPatternsStudents: Lian Wang Advisor: Yifu Ding

A breeze of moisturized air over the surface of an evaporating polymer solution can lead to well

ordered 3D water droplets condensed within the vitrified polymer films. Such 3D “breath figures” have



attracted significant interests over a broad range of applications. However, all the “breath figures” that have been created to date are limited to close packed honey-comb pattern (HCP), which is due to the weak and non-directional interactions among the condensing water droplets. This project aims to achieve 3D arrays of “breath figures” that are beyond the HCP, by utilizing topographic and/or chemical patterned substrate to guide the “breath figures” formation. Throughout the intro-to-research period, the student is expected to:

1. Thoroughlyreviewandunderstandthefundamentalsof“breathfigures”formation,aswellasthestate‐of‐the‐artprogressesinthisfield.

2. Clearly demonstrate and evaluate the feasibilities of using topographic and or chemicalpatternstoguidethe“breathfigures”formation.

3. Identifycriticalprocessingparametersand intrinsicmaterialsproperties thatcontrol theeffectivenessofthisapproach.

ControllingSurfaceTopographiesonSeparationMembraneforFoilingMitigationandEnhancedPerformance

Student: Sajjad Maruf Advisor: Yifu Ding

Surface roughness on the membranes is known to influence the performance of various

separation membranes, from the fouling behaviors to flow resistance. However, the fundamental understanding of the role of surface roughness on the membrane performances is still lacking. This is due to the limitation on the lack of creating controlled nanoscale topography onto thin film membranes to enable quantitative comparison. This project intends to explore the exclusive role of well defined nanoscale topographic patterns on the performance of a range of separation membranes. The student is expected to meet these objectives:

1. Thoroughly review the current state‐of‐knowledge on the relationship betweenmembraneroughness,performanceandfoulingcharacteristics.

2. Conduct preliminary studies on creating well defined surface patterning on selectedmembranes,andestablishtherelationshipbetweenthese“engineeredroughness”andthemembraneperformance.

SimultaneousBreakupofPolymerNanolinesonMobileandCorrugatedPolymer‐PolymerInterface

Student: Zheng Zhang Advisor:Yifu Ding

Fabrication strategies the combines top-down and bottom-up techniques are actively researched

to create topographic features that are beyond the capability of individual techniques. A variety of novel hierarchical structures has been demonstrated, with length scales defined by both the top-down lithographic techniques as well as the physical principles that govern the bottom up assembly. One such prominent example is controlled dewetting of thin viscous polymer films on chemically, topographically



or combined chemico-topographic substrates. However, all the confined dewettings reported are limited to polymers on elastic topographic substrate, i.e. the polymer/substrate interface remain intact throughout the dewetting process. Recently, we discover that mobile and corrugated polymer-polymer interface can provide unique guidance on the instability of the patterned polymers. In particular, depending on the geometric constrains, correlated capillary instabilities can occur through “out-of-phase” (left figure) or “in-phase” (right figure) fashion, giving rises to a set of unique hierarchical patterns.

So far, the mechanism for such correlated capillary breakup remains unclear. The student is expected to:

(1) Examine/mapping out the boundary conditions for the correlated instability byplanningandconductaseriesofexperimentswithvaryingviscosityratioofpolymers,geometricconstraintsandinterfacialinteractions.

(2) Developmodelstodescribetheobservedcorrelatedinstabilitiesofthesystembylinearstabilityanalysis.

VisualizingBloodFlowandMaterialPropertiesoftheCervixinPregnancywithUltrasonographyandElastography

Student: Winston Elliott Advisor: Virginia Ferguson

Co-advisor: Dr. Antonio Barbera The cervix is a complex, “stiff” structure separating the vagina and uterus during pregnancy. Over the course of pregnancy, the cervix “ripens” by reduction of structurally supporting elements. This ripening occurs throughout pregnancy, with concurrent replacement. Because turnover does not occur at the same rate of ripening, the resulting material stiffness reduces towards the end of pregnancy. This reduced stiffness allows the infant through the birth canal. Sometimes the cervix can ripen early, creating premature birth or miscarriages due to cervical insufficiency (CI). Ultrasonography has been effectively used to illustrate blood flow in vivo. Increased metabolic activity needed to constantly ripen and replace the cervical structures could be correlated with increasing blood flow over the course of pregnancy. Correlations between this blood flow and pregnancy duration could be used to predict CI.



Studies of cervical material properties exist, but distinctions in cervical location and stage of pregnancy were not made. Population numbers, due to availability of human cervixes were reduced within these studies. Elastography could be an effective way of determining the material stiffness of the cervix over pregnancy. This would also be an effective method of predicting CI. Expected Accomplishments:

1. Understanding properties and modeling of triphasic collagenous tissue. 2. Visualizing blood flow through ultrasonography. 3. Correlating elastography and material properties within small structures.

The student will perform a complete literature review, work with our colleagues in the Department of Obstetrics at the University of Colorado at Denver School of Medicine to collect and analyze data from clinical subjects, and will perform a full review of this data for the final reports and Preliminary exam presentation.

Risk,variability,anddecision‐makinginwhole‐bodymovementsStudent: Megan O’Brien Advisor: Dr. Alaa Ahmed

An intriguing finding in postural control is the marked effect of increased risk on movement strategies. Thus far, most studies on postural control and whole-body movements are inadequate for quantifying or distinguishing between appropriate and inappropriate decision-making in these situations. When deciding how to move and approach physical limits, one must take into consideration sensorimotor variability and the associated risk. The objective of this project is to develop a novel theoretical and experimental paradigm to analyze the costs underlying goal-directed, whole-body movements using the neuroeconomic framework of statistical decision-making under conditions of risk in younger and older adults. The results of this investigation will help to improve how we analyze risk-, variability-, and age-related changes in functional performance and demonstrate a practical and powerful avenue for the assessment and treatment of movement disorders. This work will also provide a measure of appropriate or inappropriate fear-of-falling, a significant risk factor for falls in older adults and direct future research targeting injury prevention, identification of those at risk for falls, and the design of interventions. Project Description: A task will be created that is analogous to approaching the edge of a cliff. The closer you get to the edge, the better the view, but the greater chance of a fall. Subjects will stand on a force plate with an LCD screen mounted in front of them that displays a cursor and a virtual cliff. The cursor acceleration will be controlled by the subjects’ center of pressure, and subjects will make forward and backward, and side-to-side movements in low- and high-risk conditions. Risk here is defined as the known losses/gains that a person associates with a movement outcome. Performance in this task is affected by sensorimotor variability, physical limits, and any explicit and implicit risk, all of which will be controlled and varied during the experiment. The optimality of discrete movement control will also be assessed using the same task and experimental protocol for older adults, a population that naturally exhibit increased sensorimotor variability and changes in movement control when approaching physical limits. In addition, a series of dynamical stochastic optimal feedback control models will be formulated and compared to current models in their ability to accurately describe the effect of risk and age on the optimality of continuous movement trajectories in addition to the discrete endpoints.



The research project will be carried out in the Department of Integrative Physiology under the supervision of Dr. Alaa Ahmed.

Designandfabricationofthinembeddedlithium‐ionbatteriesusingatomic/molecularlayerdeposition

Student: Kristopher Holub Advisor: Yung-Cheng Lee

Description: As microelectronic devices continue to decrease in size, the challenge of miniaturizing power sources becomes more significant. The preferred battery technology in industry, a lithium-ion cell, is too bulky to be used in the next generation of thin microelectronics. This project attempts to design and fabricate a thin lithium-ion battery which is embedded within microelectronic devices. One of the greatest challenges in fabricating a thin Li-ion battery is reducing the size of the hermetic seal, cathode, anode, and electrolyte material so that the volume ratio of active material to battery structure is as high as possible. This project will utilize atomic layer deposition (ALD) or molecular layer deposition (MLD) to significantly reduce the thickness of these structures. ALD is a proven technology for both hermetic barrier coatings and protection of electrodes from expansion during charging cycles. The objective of this project is to design and fabricate a battery using ALD-enabled packaging, ALD-protected electrodes, and ALD-enabled solid electrolytes to significantly reduce the overall size of the battery and increase the volume ratio of active material to battery structures.

DesignofanExtravascularContrastAgentforPhoto‐acousticImagingAdvisor: Mark Borden

Student: Anthony Barletta Description: The ultimate goal of this project is to develop a targeted nanoparticle for use in photo-acoustic theranostics. Such a device could provide enhanced capabilities for molecular imaging and targeted therapy of cancer and other diseases. The nanoparticles are composed of liquid droplets with diameters on the order of 500 nm that vaporize into microbubbles upon exposure to ultrasound. The approach is to coat the nanoparticles with gold nanorods and nanospheres. Upon excitation with a laser, these nanorods and nanospheres convert the radiation into heat via localized surface plasmon resonance, which in turn leads to local heating of the surrounding aqueous medium, resulting in thermal expansion and droplet vaporization that generates an acoustic signal. The acoustic signal can be used for ultrasound detection. The advantage of the liquid nanoparticle is the small size, which allows it to circulate for longer periods of time. The nanoparticle will also allow for molecular imaging of tissue beyond the endothelium by leaking into the extravascular space of solid tumors. The advantage of a photo-acoustic imaging modality is the ability to image a particular region with higher sensitivity and resolution than is possible with pure ultrasound or other modalities. The project will involve developing a technique for fabricating liquid nanoparticles with a target diameter of 200-300 nm as well as measuring concentrations and size distributions. The hypothesis is that nanoparticles with diameters of 200-300 nm can be created in quantities suitable for photo-acoustic theranostics using extrusion methods. The project aims to create liquid nanoparticles in this size range. Another aim of the project is to stabilize these particles, such that their size distribution does not significantly change over a timescale of days to months. An apparatus employing an extrusion method



will be set up to create liquid nanoparticles of the desired size. The concentration and size distributions of nanoparticles created via extrusion will be measured using forward and side light scattering. Alterations to the fabrication method and apparatus will be made in an effort to increase the amount of nanoparticles of suitable size created. Such alterations include changes in extrusion pressure and in diaphragm material and porosity, among others.

SolidStateElectrolytesforImprovedLithium‐ionBatteriesStudent: Jae Ha Woo

Faculty Mentor: Se-Hee Lee Description: Research on all-solid-state rechargeable lithium-ion batteries has increased considerably in recent years due to raised concerns relating to safety hazards such as solvent leakage and flammability of liquid electrolytes used for commercial lithium-ion batteries. Due to the increased level of safety that solid electrolytes (SEs) offer, an extensive global effort is under way to produce a viable SE to replace conventional liquid electrolytes. Beyond the safety advantage, all-solid-state batteries maintain a high degree of reliability, can vary in form and design, and can be constructed with a wide variety of SE materials. Unfortunately research has yet to unveil a SE that can outperform liquid electrolyte. Inferior rate capability, low ionic conductivity, interfacial instability, and low loading of active materials are just a few of barriers that stand in the way of the commercialization of all-solid-state rechargeable lithium-ion batteries. Ideally, liquid electrolytes could be replaced by SEs that perform similarly without excessive safety issues in the future. In this proposed research project, investigations to all-solid-state lithium-ion batteries will be performed. We are expecting to gain a fundamental understanding of Li-ion battery technology in terms of material characterization and electrochemical measurements. Also, this research will focus on optimization of SEs and electrode materials in a solid-state configuration to solve the issues listed previously. Material characterization techniques will include ac impedance, x-ray diffraction, electrochemical testing, Raman analysis, and some SEM imaging.

FailureMechanismsinCMCFiberBundlesatUHTandinOxidizingEnvironments

Student: Jason Lonergan Advisor: Rishi Raj

There has been a recent interest and development of a new class of ultra high temperature (UHT) materials capable of sustained structural and chemical stability at hypersonic speeds. Silicon Carbide (SiC) fiber tows with a CVI coating of SiC constitute the base structure of the Ceramic Matrix Composite (CMC). An Environmental Barrier Coating (EBC) consisting of a Polymer Derived Ceramic (PDC) bond coat and Hafnia (Hf02) topcoat is being applied to prevent oxidation of the CMC. Preliminary oxidation tests have been conducted at (1500-1600)oC in an open air box furnace. SEM, EDS, and XRD analysis indicate that the PDC and Hafnia react to form Hafnon (HfSiO4). Current results indicate that this structure prevents any measurable oxidation of the CMC. Testing of the mechanical properties of these bundles at UHT is currently under way and design of the coating and matrix layers to blunt and prevent crack propagation will follow.



CharacterizationofPEG‐encapsulatedmicrobubblesgeneratedvialowandhighenergyperturbation

Student:Kang‐HoSongAdvisor:MarkBorden

Abstract/SummaryThegoalofthisprojectistostudythephysicalpropertiesoflipid‐encapsulatedmicrobubblesgeneratedviaperturbationofperfluorobutane(PFB)gasinthepresenceofpolymerizinglipidparticles,namelypoly(ethyleneglycol)(PEG).Previousliteraturehasdemonstratedthestabilizingeffectofpolymerencapsulationonmicrobubbles,chiefamongthesefeaturingPEGmonolayers,whichallowmicrobubblestopersistforseveraldayswithlittlechangeindimensionsorshellchemistry.Twomeansofgeneratingviablepopulationsofmicrobubblesarelowfrequency(<10,000RPM)vibrationdeliveredthroughdevicessuchasamalgamatorsandultrasonicallyactiveprobesonicators(20kHz).

NovelHighThermalconductivity&LowYieldStresscompositesforElectronicPackaging(InterConnections)

Student: Saleh Ibrahim Advisor: Rishi Raj

Lead free Interconnections are widely used in Electronic applications for next-generation devices in order to obtain green environment due to concern of toxic lead. Interconnects provide a path for charge or electron to move from one place to another. With electrons, interconnects are usually made of metals or highly doped semiconductors that provide a conductive path into the package. The best materials for creating electrical interconnects are those with low resistivity. Another function of interconnect is to provide the internal environment necessary for the device to operate reliably. This requirement varies from device to device. It can be as simple as keeping the internal environment the same as the external environment (should be moisture free). Interconnects uses solder for bonding silicon chip with copper heat sink. Solder is a low melting point metal alloy (< 300 °C), typically containing tin or indium, which is used to join two metal surfaces together. Some of the desired properties of these lead free interconnections require: (i) low melting point (ii) High thermal & electrical conductivity, (iii) High creep & fatigue resistance and (iv)High shear compliance.

HybridLevelSet–GhostFluid–AdaptiveWaveletCollocationMethodforSimulationofMulti‐Phase/Multi‐ComponentFlows

Student:NurlybekKasimovAdvisor:OlegV.Vasilyev

OverthenextyearweplantodevelopahybridLevelSet/GhostFluid/AdaptiveWaveletCollocationmethodformodelingandsimulationofmulti‐phase/multi‐componentfluidflow.TheapproachwillextendtheAdaptive



WaveletCollocationMethodbyintegratingitwithbothLevelSetandGhostFluidmethodologies.TheLevelSetapproachwillallowustoaccuratelytracktheevolutionofphaseinterfaces,whileGhostFluidmethodologywillprovideuswiththecapabilitytomodelfluidflowswithpropertydiscontinuitiessuchasdensityandviscosity.TheabilityofAdaptiveWaveletCollocationmethodtolocallyrefinethecomputationmeshintheregionsofhighgradientswillallowustohavesufficientlyfinecomputationalmeshalongtheinterfaceboundary,whichinturnallowaccuraterepresentationofmulti‐phase/multi‐componentflows.Onceallthreeapproachesareintegrated,thehybridmethodwillbeappliedtosolveanumberofproblemsinvolvingmulti‐componentimmisciblefluids.

DesignofaEMGdrivencontrollerforamulti‐DOFprosthetichandbasedonPrincipalComponentAnalysis

Student: Jacob Segil Advisor: Richard Weir

Co-advisor: Derek Reamon

The goal of this project is to develop a multi-degree of freedom (DOF) prosthesis controller that uses myoelectric signals (EMG) as control inputs and which has been dimensionally optimized using principal component analysis (PCA). Currently available multi-DOF hand prostheses cannot be fully utilized because there are fewer control inputs than the number of degrees of freedom that need to be controlled (i.e. - an underactuated system). Based on work from the neuroscience literature (Santello et al., 1998) it has been shown that grasping is a ‘low dimensional’ task. This work used PCA to quantify the principal components [number of dimensions] involved in grasping. It was found that grasping tasks could be well described by only 2 principal components. 2 principal components implies that the multi-DOF hand posture in grasping can be controlled using only 2 degrees of control. This is an encouraging finding since current clinical upper limb prosthetic practice indicates 3, or 4, indepedent myoelectric sites can be located on the residual limb of a typical person with a transradial amputation.

We propose to develop a hand posture controller based on the 2 principal components described by Santello et al. and driven using 3 or 4 myoelectric sites. This project involves an intensive literature review of the use of PCA in grasping and prosthesis control, the development of a controller based on PCA of grasping data, and the integration of conventional myoelectric signals into the controller.

MesoscaleThermalandThermoelectricTransportinCarbonNanotube(CNT)andGrapheneNanocomposites

Student: Zhixin Sun Faculty: Ronggui Yang

Carbon Nanotube (CNT) and Graphene have been demonstrated to have very large thermal conductivity and electrical conductivity. However, the thermoelectric Seebeck coefficient is very low in these materials and the interface thermal resistance for inter-tube or inter-layer connections is very high, which makes these materials difficult to scale up for either heat conducting materials (such as thermal interface materials or heat spreaders) or thermoelectric energy conversion materials. More importantly,



due to the dimensionality and high aspect ratio, it is very challenging to study the mesoscale thermal or electrical transport in CNT and graphene nanocomposites. In this work, mesoscale physical models and simulation tools will be developed to understand the thermal and thermoelectric transport phenomena in CNT and graphene nanocomposites with an ultimate objective to design nanocomposites with tunable thermal conductivity for thermal management and energy conversion applications.

Surface‐MountedCapacitiveMicrosensorsforIn‐SituMonitoringofMembrane‐BasedDesalinationProcesses

Student: Hao Xu Faculty: Victor Bright and Alan Greenberg

Micro- and Nanoporous polymeric membranes are used in numerous liquid-separation processes. Of particular engineering, economic and social interest is the growing demand for clean, fresh water. This has led to the explosive growth of membrane-based water-treatment processes in many parts of the world. One process of key importance is desalination. Seawater along coastal regions in arid locations is often employed as the feed source. Although highly saline inland brackish waters are more readily available, such sources are not commonly used because of the high concentrations of dissolved salts. The pretreatment costs for brackish waters can be relatively high and the amount of water that can be recovered is correspondingly low due to scaling of insoluble salts on the membrane surface. Deposition and growth of this scaling layer can significantly affect membrane performance and/or damage the membrane. Depending on the nature of the scalant, the scaling deposits may or may not be removable. Although anti-scalants are now routinely used to improve membrane lifetime, they are expensive and are of only limited utility for increasing water recovery from desalination. Therefore, there is considerable interest in novel approaches to limit membrane scaling.

Current membrane-based liquid-separation processes are generally monitored by external volumetric flow-based techniques. Such measurements, however, do not provide direct information on the initiation and growth of membrane scaling. The proposed project seeks to develop and test a prototype membrane-surface-mounted capacitive microsensor device that will be incorporated into a laboratory-scale separation flow cell. This in-situ sensor will provide real-time measurements of the local concentration of dissolved solutes in the fluid feed stream, thus providing a means to determine the optimal timing for remediation measures during the filtration process. The project will involve investigation of the properties of electrolytic solutions and as well as fluid mechanics and mass transport during filtrations. Microfabrication techniques will be studied and employed as necessary to develop and improve the functioning sensor system. The overall goal of this project is to design, fabricate, and characterize the capacitive surface-mounted microsensors under laboratory-controlled membrane-scaling experiments. The project is highly interdisciplinary involving aspects of mechanics, mass transport, electrochemistry, materials, signal processing, data acquisition, instrumentation, design and fabrication. The project has a high probability of providing future thesis support for the successful student.

liquid spray fuel injection studies using direct numerical simulation …€¦ · ·...

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