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Title: Characterization, Classification, and Genesis of Seismocardiographic Signals.
Creator: Taebi, Amirtaha, Mansy, Hansen, Kassab, Alain, Huang, Helen, Vosoughi, Azadeh, University of Central Florida
Abstract / Description: Seismocardiographic (SCG) signals are the acoustic and vibration induced by cardiac activity measured non-invasively at the chest surface. These signals may offer a method for diagnosing and monitoring heart function. Successful classification of SCG signals in health and disease depends on accurate signal characterization and feature extraction.In this study, SCG signal features were extracted in the time, frequency, and time-frequency domains. Different methods for estimating time-frequency...
Show moreSeismocardiographic (SCG) signals are the acoustic and vibration induced by cardiac activity measured non-invasively at the chest surface. These signals may offer a method for diagnosing and monitoring heart function. Successful classification of SCG signals in health and disease depends on accurate signal characterization and feature extraction.In this study, SCG signal features were extracted in the time, frequency, and time-frequency domains. Different methods for estimating time-frequency features of SCG were investigated. Results suggested that the polynomial chirplet transform outperformed wavelet and short time Fourier transforms.Many factors may contribute to increasing intrasubject SCG variability including subject posture and respiratory phase. In this study, the effect of respiration on SCG signal variability was investigated. Results suggested that SCG waveforms can vary with lung volume, respiratory flow direction, or a combination of these criteria. SCG events were classified into groups belonging to these different respiration phases using classifiers, including artificial neural networks, support vector machines, and random forest. Categorizing SCG events into different groups containing similar events allows more accurate estimation of SCG features.SCG feature points were also identified from simultaneous measurements of SCG and other well-known physiologic signals including electrocardiography, phonocardiography, and echocardiography. Future work may use this information to get more insights into the genesis of SCG.
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Date Issued: 2018
Identifier: CFE0007106, ucf:51944
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007106

Title: Fluid Dynamics Modeling and Sound Analysis of a Bileaflet Mechanical Heart Valve.
Creator: Khalili, Fardin, Mansy, Hansen, Kassab, Alain, Steward, Robert, Zaurin, Ricardo, University of Central Florida
Abstract / Description: Cardiovascular disease (CVD) is one of the main causes of death in the world. Some CVD involve severe heart valve disease that require valve replacement. There are more than 300,000 heart valves implanted worldwide, and about 85,000 heart valve replacements in the US. Approximately half of these valves are mechanical. Artificial valves may dysfunction leading to adverse hemodynamic conditions. Understanding the normal and abnormal valve function is important as it help improve valve designs....
Show moreCardiovascular disease (CVD) is one of the main causes of death in the world. Some CVD involve severe heart valve disease that require valve replacement. There are more than 300,000 heart valves implanted worldwide, and about 85,000 heart valve replacements in the US. Approximately half of these valves are mechanical. Artificial valves may dysfunction leading to adverse hemodynamic conditions. Understanding the normal and abnormal valve function is important as it help improve valve designs. Modeling of heart valve hemodynamics using computational fluid dynamics (CFD) provides a comprehensive analysis of flow, which can potentially help explain clinical observations and support therapeutic decision-making. This detailed information might not be accessible with in-vivo measurements. On the other hand, finite element analysis (FEA), is an efficient way to analyze the interactions of blood flow with blood vessel and tissue layers. In this project both CFD and FEA simulations were performed to investigate the flow-induced sound generation and propagation of sound waves through a tissue-like material. This method is based on mapping the transient pressure (force) fluctuations on the vessel wall and solving for the structural vibrations in the frequency domain. These vibrations would then be detected as sound on the epidermal surface. Advantages of the methods used in the current study include: (a) capability of providing accurate solution with a faster solution time; (b) inclusion of the fluid(-)structure interaction between blood flow and the arterial wall; and (c) accurately capturing some of the spectral features of the velocity fluctuation measured over the epidermal surface.
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Date Issued: 2018
Identifier: CFE0007029, ucf:52038
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007029

Title: A Localized Blended RBF Collocation Method for Effective Shock Capturing.
Creator: Harris, Michael, Kassab, Alain, Moslehy, Faissal, Divo, Eduardo, Chopra, Manoj, University of Central Florida
Abstract / Description: Solving partial differential equations (PDEs) can require numerical methods, especially for non-linear problems and complex geometry. Common numerical methods used today are the finite difference method (FDM), finite element method (FEM) and the finite volume method (FVM). These methods require a mesh or grid before a solution is attempted. Developing the mesh can require expensive preprocessing time and the quality of the mesh can have major effects on the solution. In recent years, meshless...
Show moreSolving partial differential equations (PDEs) can require numerical methods, especially for non-linear problems and complex geometry. Common numerical methods used today are the finite difference method (FDM), finite element method (FEM) and the finite volume method (FVM). These methods require a mesh or grid before a solution is attempted. Developing the mesh can require expensive preprocessing time and the quality of the mesh can have major effects on the solution. In recent years, meshless methods have become a research interest due to the simplicity of using scattered data points. Many types of meshless methods exist stemming from the spectral or pseudo-spectral methods, but the focus of this research involves a meshless method using radial basis function (RBF) interpolation. Radial basis functions (RBF) interpolation is a class of meshless method and can be used in solving partial differential equations. Radial basis functions are impressive because of the capability of multivariate interpolation over scattered data, even for data with discontinuities. Also, radial basis function interpolation is capable of spectral accuracy and exponential convergence. For infinitely smooth radial basis functions such as the Hardy Multiquadric and inverse Multiquadric, the RBF is dependent on a shape parameter that must be chosen properly to obtain accurate approximations. The optimum shape parameter can vary depending on the smoothness of the field. Typically, the shape parameter is chosen to be a large value rendering the RBF flat and yielding high condition number interpolation matrix. This strategy works well for smooth data and as shown to produce phenomenal results for problems in heat transfer and incompressible fluid dynamics. The approach of flat RBF or high condition matrices tends to fail for steep gradients and shocks. Instead, a low-value shape parameter rendering the RBF steep and the condition number of the interpolation matrix small should be used in the presence of steep gradients or shocks. This work demonstrates a method to capture steep gradients and shocks using a blended RBF approach. The method switches between flat and steep RBF interpolation depending on the smoothness of the data. Flat RBF or high condition number RBF interpolation is used for smooth regions maintaining high accuracy. Steep RBF or low condition number RBF interpolation provides stability for steep gradients and shocks. This method is demonstrated using several numerical experiments such as 1-D advection equation, 2-D advection equation, Burgers equation, 2-D inviscid compressible Euler equations, and the Navier-Stokes equations.
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Date Issued: 2018
Identifier: CFE0007332, ucf:52108
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007332

Title: Probing the Influence of Cx43 and Glucose on Endothelial Biomechanics.
Creator: Islam, Md Mydul, Steward, Robert, Kassab, Alain, Mansy, Hansen, Willenberg, Bradley, University of Central Florida
Abstract / Description: Endothelial cells (ECs) form the innermost layer of all vasculature and constantly receive both biochemical and biomechanical signals, yielding a plethora of biomechanical responses. In response to various biochemical or biomechanical cues, ECs have been documented to generate biomechanical responses such as tractions and intercellular stresses between the cell and substrate and between adjacent cells in a confluent monolayer, respectively. Thus far, the ability of endothelial tight junctions...
Show moreEndothelial cells (ECs) form the innermost layer of all vasculature and constantly receive both biochemical and biomechanical signals, yielding a plethora of biomechanical responses. In response to various biochemical or biomechanical cues, ECs have been documented to generate biomechanical responses such as tractions and intercellular stresses between the cell and substrate and between adjacent cells in a confluent monolayer, respectively. Thus far, the ability of endothelial tight junctions and adherens junctions to transmit intercellular stresses has been actively investigated, but the role of gap junctions is currently unknown. In addition, there is no report of the independent influence of hyperglycemia on endothelial biomechanics present in the literature. To fill these gaps, we conducted a two-fold study where we investigated the influence of endothelial gap junction Cx43 and hyperglycemia in endothelial tractions and intercellular stress generation. In the first study, we selectively disrupted and enhanced EC gap junction Cx43 by using 2',5'-dihydroxychalcone and retinoic acid, respectively and in the second study, we cultured ECs in both normal glucose and hyperglycemic condition for 10 days. In both studies, tractions and intercellular stresses were calculated using traction force microscopy (TFM) and monolayer stress microscopy (MSM), respectively. Our results reveal that Cx43 downregulation increased as well as decreased endothelial avg. normal intercellular stresses in response to a low (0.83 (&)#181;M) and a high dose (8.3 (&)#181;M) chalcone treatment, respectively, while Cx43 upregulation decreases avg. normal intercellular stresses in both treatment conditions (2.5 (&)#181;M and 25 (&)#181;M) compared to control. In addition, we observed a decrease in intercellular stresses with hyperglycemic condition compared to control. The results we present here represent, for the first time, detailed and comprehensive biomechanical analysis of endothelial cells under the influence of glucose and the gap junction Cx43. We believe our results will provide valuable insights into endothelial permeability, barrier strength as well as leading to a greater understanding of overall endothelial mechanics.
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Date Issued: 2019
Identifier: CFE0007819, ucf:52805
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007819

Title: Investigation of Novel Fin Structures Enhancing Micro Heat Sink Thermal Performance.
Creator: Ismayilov, Fuad, Peles, Yoav, Kassab, Alain, Putnam, Shawn, Akturk, Ali, University of Central Florida
Abstract / Description: Operating temperature in electronics applications is continuously increasing. Therefore, for the past few decades, high heat flux removing micro heat sinks are investigated in terms of heat transfer effectiveness. This study generally concentrates on improving the passive heat transfer techniques. Micro heat sinks used in experiments are fabricated using MEMS techniques. Resistance temperature detectors, RTDs, were used for temperature measurements. The experimental data was obtained for...
Show moreOperating temperature in electronics applications is continuously increasing. Therefore, for the past few decades, high heat flux removing micro heat sinks are investigated in terms of heat transfer effectiveness. This study generally concentrates on improving the passive heat transfer techniques. Micro heat sinks used in experiments are fabricated using MEMS techniques. Resistance temperature detectors, RTDs, were used for temperature measurements. The experimental data was obtained for single and two phase flow regions; however, only single phase flow results were considered in numerical simulations. Numerical validations were performed on the micro heat sinks, including cylinder and hydrofoil shaped pin fins. Following the validation phase, optimization has been performed to further improve the hydraulic and thermal performance. DOE study showed that the chord length and leading edge size of the hydrofoil pin fin are significant contributors to the thermal performance. The ranges of geometrical variables were identified and fed into multi-objective optimization cycles implementing the multi-objective genetic algorithm. The optimization objectives were to minimize pumping requirements while enhancing the local and global heat transfer effectiveness over the surface of the heater in single phase flow environment. A broad range of geometries were obtained with an acceptable tradeoff between thermal and hydraulic performance for low Reynolds number. Additionally, tandem geometries were investigated and showed that higher heat transfer effectiveness could be obtained with acceptable pumping power requirements. The importance of such optimization studies before the experimental testing is highlighted, and novel geometries are presented for further experimental investigations. Thermal performance improvement of 28% was obtained via implementing proposed geometries with only a 12% pressure drop increase. Local heat transfer optimization, aiming to decrease the local temperatures were also performed using doublet pin fin configurations. Results showed that tandem hydrofoils could control the flow with minimum pressure drops while reaching the desired low local temperatures.
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Date Issued: 2019
Identifier: CFE0007821, ucf:52828
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007821

Title: Hybrid Multi-Objective Optimization of Left Ventricular Assist Device Outflow Graft Anastomosis Orientation to Minimize Stroke Rate.
Creator: Lozinski, Blake, Kassab, Alain, Mansy, Hansen, DeCampli, William, University of Central Florida
Abstract / Description: A Left Ventricular Assist Device (LVAD) is a mechanical pump that is utilized as a bridge to transplantation for patients with a Heart Failure (HF) condition. More recently, LVADs have been also used as destination therapy and have provided an increase in the quality of life for patients with HF. However, despite improvements in VAD design and anticoagulation treatment, there remains a significant problem with VAD therapy, namely drive line infection and thromboembolic events leading to...
Show moreA Left Ventricular Assist Device (LVAD) is a mechanical pump that is utilized as a bridge to transplantation for patients with a Heart Failure (HF) condition. More recently, LVADs have been also used as destination therapy and have provided an increase in the quality of life for patients with HF. However, despite improvements in VAD design and anticoagulation treatment, there remains a significant problem with VAD therapy, namely drive line infection and thromboembolic events leading to stroke. This thesis focuses on a surgical maneuver to address the second of these issues, guided by previous steady flow hemodynamic studies that have shown the potential of tailoring the VAD outflow graft (VAD-OG) implantation in providing up to 50% reduction in embolization rates. In the current study, multi-scale pulsatile hemodynamics of the VAD bed is modeled and integrated in a fully automated multi-objective shape optimization scheme in which the VAD-OG anastomosis along the Ascending Aorta (AA) is optimized to minimize the objective function which include thromboembolic events to the cerebral vessels and wall shear stress (WSS). The model is driven by a time dependent pressure and flow boundary conditions located at the boundaries of the 3D domain through a 50 degree of freedom 0D lumped parameter model (LPM). The model includes a time dependent multi-scale Computational Fluid Dynamics (CFD) analysis of a patient specific geometry. Blood rheology is modeled as using the non-Newtonian Carreua-Yasuda model, while the hemodynamics are that of a laminar and constant density fluid. The pulsatile hemodynamics are resolved using the commercial CFD solver StarCCM+ while a Lagrangian particle tracking scheme is used to track constant density particles modeling thromobi released from the cannula to determine embolization rated of thrombi. The results show that cannula anastomosis orientation plays a large role when minimizing the objective function for patient derived aortic bed geometry used in this study. The scheme determined the optimal location of the cannula is located at 5.5 cm from the aortic root, cannula angle at 90 degrees and coronal angle at 8 degrees along the AA with a peak surface average WSS of 55.97 dy/cm2 and stroke percentile of 12.51%. A Pareto front was generated showing the range of 9.7% to 44.08% for stroke and WSS of 55.97 to 81.47 dy/cm2 ranged over 22 implantation configurations for the specific case studied. These results will further assist in the treatment planning for clinicians when implementing a LVAD.
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Date Issued: 2019
Identifier: CFE0007833, ucf:52827
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007833

Title: Detection of DDH in Infants and Children Using Audible Acoustics.
Creator: Hassan, Tanvir, Mansy, Hansen, Song, Sang-Eun, Kassab, Alain, University of Central Florida
Abstract / Description: Detection of developmental dysplasia of the hip (DDH) in infants and children is important as it leads to permanent hip instability. Current methods for detecting DDH, such as ultrasound and x-rays, are relatively expensive and need qualified medical personnel to administer the test. Furthermore, x-ray ionizing radiation can have potential harmful effects. In the current study, an acoustic non-invasive and simple approach was investigated for detection of DDH. Different benchtop simplified...
Show moreDetection of developmental dysplasia of the hip (DDH) in infants and children is important as it leads to permanent hip instability. Current methods for detecting DDH, such as ultrasound and x-rays, are relatively expensive and need qualified medical personnel to administer the test. Furthermore, x-ray ionizing radiation can have potential harmful effects. In the current study, an acoustic non-invasive and simple approach was investigated for detection of DDH. Different benchtop simplified models and pig models were constructed and tested. Models were stimulated with band-limited white acoustic noise (10-2500 Hz) and the response of the models was measured. The power spectrum density, transfer function, and coherence were determined for different hip dysplasia levels and for normal cases. Results showed that the power spectrum density, transfer function, and coherence were affected by dysplasia occurrence. Effects appear larger for more severe dysplastic hips. This suggests that the proposed approach may have potential for DDH detection.
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Date Issued: 2019
Identifier: CFE0007816, ucf:52350
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007816

Title: Controlled Bubble Dynamics Inside Micropillar Arrays.
Creator: Khalil Arya, Faraz, Peles, Yoav, Gou, Jihua, Kassab, Alain, Abdolvand, Reza, University of Central Florida
Abstract / Description: Bubble dynamics inside micro domains was manipulated and used to pump liquid. Micropillars were formed inside two 1.5 mm wide and 220 (&)#181;m high microchannels with a length of 23 mm. One microchannel had three arrays of micropillars with diameters of 40 (&)#181;m and the other had a single array of micropillars with diameters of 30 (&)#181;m. An array of five 200 (&)#181;m by 200 (&)#181;m heaters was deposited inside these micropillar arrays and was used to control bubble size and...
Show moreBubble dynamics inside micro domains was manipulated and used to pump liquid. Micropillars were formed inside two 1.5 mm wide and 220 (&)#181;m high microchannels with a length of 23 mm. One microchannel had three arrays of micropillars with diameters of 40 (&)#181;m and the other had a single array of micropillars with diameters of 30 (&)#181;m. An array of five 200 (&)#181;m by 200 (&)#181;m heaters was deposited inside these micropillar arrays and was used to control bubble size and trajectory. A sequential power switching of the heaters was used to pump liquid in a desired direction with a flow rate of up to 133 (&)#181;l/min for the three arrays micropillars microchannel and up to 44.4 (&)#181;l/min for the single array micropillars device.
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Date Issued: 2018
Identifier: CFE0007757, ucf:52381
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007757

Title: Multiphase Flow Modeling of Molten Metal Atomization at High Gas Pressure.
Creator: Hanthanan Arachchilage, Kalpana, Kumar, Ranganathan, Sohn, Yongho, Kassab, Alain, Shivamoggi, Bhimsen, University of Central Florida
Abstract / Description: The high-pressure gas atomization is well known as one of the best powder manufacturing processes due to its controllability over powder size distribution. However, with the continuous improvement of new alloys, optimizing the operating parameters to maximize the yield is costly and time-consuming. Therefore, it is essential to understand the high-pressure gas atomization process and the effects of different operational parameters on the powder size distribution.Two-phase numerical...
Show moreThe high-pressure gas atomization is well known as one of the best powder manufacturing processes due to its controllability over powder size distribution. However, with the continuous improvement of new alloys, optimizing the operating parameters to maximize the yield is costly and time-consuming. Therefore, it is essential to understand the high-pressure gas atomization process and the effects of different operational parameters on the powder size distribution.Two-phase numerical simulations are performed to capture the interfacial dynamic during the atomization process and to obtain the effects of gas pressure, melt flow rate, and thermophysical properties of atomizing gas and the molten metal. The Volume of Fluid (VOF) model is used to capture the melt-gas interface, and in-house post-processing code is developed to obtain the droplet size distributions. Three-dimensional geometry of an annular-slit close-coupled gas atomizer is utilized to investigate the primary atomization process. The current grid resolution is sufficient forcapturing primary atomization and some characteristics of the secondary atomization, but it is not adequate to capture all the length scales in secondary atomization. Qualitative comparisons of the cumulative volume graphs indicate that this numerical approach is capable of capturing the trends in the atomization process as in the experiments. It is found that a combination of several interfacial instabilities governs the atomization process. Simulations corresponding to different gas pressures show that the atomizationcharacteristics remain unchanged irrespective of the gas pressure. However, it is found that the rate of the evolution and the effectiveness of the atomization process increases with the gas pressure. Three melts (aluminum, steel, and an artificial material with intermediate thermophysical properties) are used to investigate the effects of the molten metal properties and found that the rate of the atomization process decreases with increasing melt density, and the yield of the atomized powder is seen to increase. The flow characteristics remain unchanged for all three melts. The melt flow is strongly correlated with flow characteristics and interfacial instability.
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Date Issued: 2019
Identifier: CFE0007814, ucf:52342
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007814

Title: Energy Expenditure and Stability During Self-Paced Walking on Different Slopes.
Creator: Raffaelli, Alanna, Huang, Helen, Fu, Qiushi, Kassab, Alain, University of Central Florida
Abstract / Description: Metabolic power and cost of transport (COT) are common quantifiers for effort when performing tasks including walking and running. Most studies focus on using a range of normal walking speeds over level ground or varied slopes. However, these studies use fixed-speed conditions. Fatigue, stability, metabolic expenditure, heart rate, and many other factors contribute to normal walking speed varying over time. This study aimed to show that allowing a subject to walk with a self-paced speed...
Show moreMetabolic power and cost of transport (COT) are common quantifiers for effort when performing tasks including walking and running. Most studies focus on using a range of normal walking speeds over level ground or varied slopes. However, these studies use fixed-speed conditions. Fatigue, stability, metabolic expenditure, heart rate, and many other factors contribute to normal walking speed varying over time. This study aimed to show that allowing a subject to walk with a self-paced speed should correlate to a minimum COT at a given slope. This study also aimed to determine if a preferred slope exists based on minimizing metabolic expenditure or maximizing stability. In this study, subjects walked at four different speed conditions including three fixed speeds (0.75 m/s, 1.0 m/s, 1.25 m/s) and their self-paced speed at five different slopes (-6(&)deg;, -3(&)deg;, 0(&)deg;, 3(&)deg;, 6(&)deg;) while metabolic energy expenditure and motion were recorded. The minimum COT occurred at a 3(&)deg; decline. At this slope, some subjects preferred to walk at a faster speed compared to level ground, whereas other subjects walked with a slower speed compared to level ground. Thus, there was a greater range of self-paced speeds, from 0.745 m/s-2.045 m/s. In comparison, at a 6(&)deg; incline, the range of self-paced speeds was much smaller, from 0.767 m/s-1.434 m/s. The variance among self-paced speeds and slope conditions between subjects suggests that COT, alone, does not explain walking decisions; stability might play a greater role than initially believed. These results provide greater insight into why humans choose to walk at a certain speed over a range of slopes and terrains.
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Date Issued: 2019
Identifier: CFE0007515, ucf:52629
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007515

Title: Compressibility Effect on Turbulent Flames and Detonation Initiation and Propagation.
Creator: Sosa, Jonathan, Ahmed, Kareem, Kassab, Alain, Kapat, Jayanta, University of Central Florida
Abstract / Description: This work presents the first measurement of turbulent burning velocities of a highly-turbulent compressible standing flame induced by shock-driven turbulence in a Turbulent Shock Tube. High-speed schlieren, chemiluminescence, PIV, and dynamic pressure measurements are made to quantify flame-turbulence interaction for high levels of turbulence at elevated temperatures and pressure. Distributions of turbulent velocities, vorticity and turbulent strain are provided for regions ahead and behind...
Show moreThis work presents the first measurement of turbulent burning velocities of a highly-turbulent compressible standing flame induced by shock-driven turbulence in a Turbulent Shock Tube. High-speed schlieren, chemiluminescence, PIV, and dynamic pressure measurements are made to quantify flame-turbulence interaction for high levels of turbulence at elevated temperatures and pressure. Distributions of turbulent velocities, vorticity and turbulent strain are provided for regions ahead and behind the standing flame. The turbulent flame speed is directly measured for the high-Mach standing turbulent flame. From measurements of the flame turbulent speed and turbulent Mach number, transition into a non-linear compressibility regime at turbulent Mach numbers above 0.4 is confirmed, and a possible mechanism for flame generated turbulence and deflagration-to-detonation transition is established.Additionally, this study presents the exploration of detonation wave propagation dynamics in premixed supersonic flows using a novel rotating detonation engine (RDE) configuration. An RDE with a coupled linear extension, referred to as ?DE, is used to divide detonations traveling radially in the RDE into linearly propagating waves. A tangential propagating wave is directed down a modular tangential linearized extension to the engine for ease of optical diagnostics and hardware configuration investigations. A premixed Mach 2 supersonic linear extension is coupled to the ?DE to investigate the effects of varying crossflow configurations for detonation propagation, particularly the interaction between detonations and supersonic reactive mixtures. Detonation waves are generated at the steady operating frequency of the RDE and visualized using high speed schlieren and broadband OH* chemiluminescence imaging. The stagnation pressure was varied from over- to ideally-expanded supersonic regimes. Experimental analysis of detonation interaction with the supersonic regimes show that the detonation propagates freely in the ideally-expanded regime. Deflagration-to-detonation transition (DDT) occurs in the over-expanded regime. Based on the data collected, the DDT process favors supersonic flow with higher source pressures. Lastly, this work presents the experimental evidence of controlled detonation wave initiation and propagation in hydrogen-air premixed hypersonic Mach 5 flows. A Mach 5 high-enthalpy facility is used to provide the premixed hydrogen-air stream targeted to match the boundary conditions (Chapman-Jouguet, CJ) for stable detonations. The work shows for the first-time flame deflagration-to-detonation transition through coupled mechanism of turbulent flame acceleration and shock-focusing in a premixed Mach 5 flow. The paper defines three new distinct regimes in a Mach 5 premixed flow: Deflagration-to-Detonation Transition (DDT), Unsteady Compressible Turbulent Flames, and Shock-Induced Combustion. With rising national interest in hypersonics and reduced combustion emissions, the discovery and classification of these new combustion regimes allows for a possible pathway to develop and integrate detonation technology enabling hypersonic propulsion technology and advanced power systems.
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Date Issued: 2019
Identifier: CFE0007534, ucf:52607
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007534

Title: Development of a Single Sensor Approach for Capturing Three-Dimensional, Time Resolved Flame and Velocity Information.
Creator: Reyes, Jonathan, Ahmed, Kareem, Kassab, Alain, Kapat, Jayanta, University of Central Florida
Abstract / Description: Performing non-intrusive measurements is the key to acquiring accurate information representative of what is being observed. The act of measuring often changes the environment being observed altering the information that is being obtained. Due to this, the community of fluid scientists have gravitated towards using laser-based measurements to observe the phenomena occurring in their experiments. The study of fluids has advanced since this point, utilizing techniques such as planar laser...
Show morePerforming non-intrusive measurements is the key to acquiring accurate information representative of what is being observed. The act of measuring often changes the environment being observed altering the information that is being obtained. Due to this, the community of fluid scientists have gravitated towards using laser-based measurements to observe the phenomena occurring in their experiments. The study of fluids has advanced since this point, utilizing techniques such as planar laser induced florescence (PLIF), particle image velocimetry (PIV), laser doppler velocimetry (LDV), particle doppler anemometry (PDA), etc. to acquire chemical species information and velocity information. These techniques, though, are inherently two-dimensional and cannot fully describe a flow field. In the area of reacting flow fields (combustion) acquiring the local fuel to air ratio information is increasingly important. Without it, scientist must rely on global one-dimensional metering techniques to correlate the fuel to air ratio of their flow field of interest. By knowing the fuel to air ratio locally and spatially across a flame, the location of products and reactants can be deduced, giving insight into any inefficiencies associated with a burner. Knowing the spatial fuel air field also gives insights into the density gradient associated with the flow field. Discussed in this work will be the development of a non-intrusive local fuel-air measurement technique and an expansion of the PIV technique into the third dimension, tomographic PIV, utilizing only one camera to do so for each measurement. The local fuel-air measurement is performed by recording two species (C2* and CH*) simultaneously and calibrating their ratio to the known fuel-air field. Tomographic PIV is performed by utilizing fiber coupling to acquire multiple viewpoints utilizing a single camera.
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Date Issued: 2019
Identifier: CFE0007523, ucf:52602
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007523

Title: Cavitation and heat transfer over micro pin fins.
Creator: Nayebzadeh, Arash, Peles, Yoav, Chow, Louis, Kassab, Alain, Plawsky, Joel, University of Central Florida
Abstract / Description: With the dramatic increase in the usage of compact yet more powerful electronic devices, advanced cooling technologies are required to maintain delicate electronic components below their maximum allowable temperatures and prevent them from failure. One solution is to use innovative pin finned heat sinks. This research is centered on the evaluation of hydrodynamic cavitation properties downstream pin fins and extended toward single-phase heat transfer enhancement of array of pin fins in...
Show moreWith the dramatic increase in the usage of compact yet more powerful electronic devices, advanced cooling technologies are required to maintain delicate electronic components below their maximum allowable temperatures and prevent them from failure. One solution is to use innovative pin finned heat sinks. This research is centered on the evaluation of hydrodynamic cavitation properties downstream pin fins and extended toward single-phase heat transfer enhancement of array of pin fins in microchannel. In this work, transparent micro-devices capable of local wall temperature measurements were micro fabricated and tested. Various experimental methods, numerical modeling and advanced data processing techniques are presented. Careful study over cavitation phenomena and heat transfer measurement downstream pin fins were performed.Hydrodynamic cavitation downstream a range of micro pillar geometries entrenched in a microchannel were studied. Three modes of cavitation inception were observed and key parameters of cavitation processes, such as cavity length and angle of attachment, were compared among various micro pillar geometries. Cavity angle of attachments were predominantly related to the shape of the micro pillar. Fast Fourier transformation (FFT) analysis of the cavity image intensity revealed transverse cavity shedding frequencies in various geometries and provided an estimation for vortex shedding frequencies.Experimental and numerical heat transfer studies over array of pin fins were carried out to find out the influence of lateral interactions of fluid flow on the enhancement of heat transfer. Local temperature measurements combined with a conjugate fluid flow and heat transfer modeling revealed the underlying heat transfer mechanisms over pin fin arrays.
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Date Issued: 2019
Identifier: CFE0007690, ucf:52407
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007690

Title: Investigation of oxy-fuel combustion behind reflected shockwaves.
Creator: Pryor, Owen, Vasu Sumathi, Subith, Kapat, Jayanta, Kassab, Alain, University of Central Florida
Abstract / Description: Supercritical carbon dioxide has brought about new questions on the chemical kinetics of several small hydrocarbon fuels and the effects of carbon dioxide as the primary diluent on the different fuels. This report presents work on the ignition delay times and several species time-histories of methane, ethylene and syngas over a range of conditions. All experiments were conducted behind reflected shock waves using two different shock tubes. The ignition delay times were measured using a GaP...
Show moreSupercritical carbon dioxide has brought about new questions on the chemical kinetics of several small hydrocarbon fuels and the effects of carbon dioxide as the primary diluent on the different fuels. This report presents work on the ignition delay times and several species time-histories of methane, ethylene and syngas over a range of conditions. All experiments were conducted behind reflected shock waves using two different shock tubes. The ignition delay times were measured using a GaP photodetector to measure the emission of light. The species time-histories were measured using single laser spectroscopy. The effect of CO2 as a diluent on the fluid dynamics of the system were also examined using high-speed camera images. It was determined that the ignition delay times and fuel time-histories were able to be accurately predicted by mechanisms in the literature for pressures up to 30 atm but the literature mechanisms were unable to predict the carbon monoxide time-histories beyond qualitative trends for the various fuels. It was also determined that the carbon monoxide had a string effect on the fluid dynamics of the experiments resulting in a significantly smaller chemical reaction zone. Experiments were also performed to examine the effects of water as a diluent with a ratio up to 66% of the total diluent on the ignition delay times. Using the experimental data, a global kinetic mechanism was created for methane and syngas to predict the ignition delay times and the carbon monoxide time-histories for pressures up to 300 atm.
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Date Issued: 2018
Identifier: CFE0007236, ucf:52216
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007236

Title: Heat Transfer and Friction Augmentation in a Narrow Rectangular Duct with Symmetrical and Non-Symmetrical Wedge-Shaped Turbulators.
Creator: Valentino, Michelle, Kapat, Jayanta, Deng, Weiwei, Kassab, Alain, University of Central Florida
Abstract / Description: The need for cleaner and more fuel efficient means to produce electricity is growing steadily. Advancements in cooling technologies contribute to the improvements in turbine efficiency and are used for gas turbines and for power generation in automotive, aviation, as well as in naval applications, and many more. Studies introducing turbulators on walls of internal cooling channels, which can be applied to hot gas components and in recuperative heat exchangers, have been reviewed for their...
Show moreThe need for cleaner and more fuel efficient means to produce electricity is growing steadily. Advancements in cooling technologies contribute to the improvements in turbine efficiency and are used for gas turbines and for power generation in automotive, aviation, as well as in naval applications, and many more. Studies introducing turbulators on walls of internal cooling channels, which can be applied to hot gas components and in recuperative heat exchangers, have been reviewed for their ability to promote heat transfer in the channel while observing pressure loss caused by adding the features. Several types of turbulators have been studied; ribs, pin fins, dimples, wedges, and scales are some examples of features that have been added to walls of internal cooling channels or heat exchangers to increase heat transfer. This study focuses on two types of wedge turbulator designs, a full symmetrical wedge and a half, or non-symmetrical right-triangular wedge for the purpose of disrupting the thermal boundary layer close to hot walls without causing large-scale mixing and pressure drops. There are two sizes of the wedges, the first set of full and half wedges have an e/Dh=0.10 with the second at e/Dh=0.40, a feature that fills the height of the boundary layer. There are six cases studied, two one-wall and four two-wall cases in a 2:1 aspect ratio channel at Reynolds numbers of 10,000, 20,000, 30,000, and 40,000. Two experimental setups are utilized: a segmented copper block and transient TLC, along with numerical simulation for computational flow visualization. Wall temperature data is collected from all four walls for the copper experimental setup and three walls on the transient TLC setup. The fourth wall of the acrylic test section for the transient TLC tests is utilized for pressure testing, where static pressure ports are placed along the side wall. Although the small features did not show large influence in heat transfer on the side walls as much as the larger features or as high of heat transfer on the featured walls, the minimal pressure loss in the channel kept overall thermal performance of the small two wall full wedge features very high. The case of the large half wedge on two walls also showed very high thermal performance, having pressure loss values nearly half of the same sized (length and height) full wedge feature while having the ability to incorporate side walls into the overall heat transfer enhancement. The results found in the experimental setups are supported by the visualization of flow characteristics from the numerical testing. Comparing the initial wedge study to recent full rib studies show the wedges have similar improvements in heat transfer to the full rib cases with friction augmentations 5 to 10 times lower than the full rib cases. Further improvements to wedge heat transfer and pressure drop can be done by determining optimal wedge size and orientation.
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Date Issued: 2011
Identifier: CFE0004489, ucf:49299
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004489

Title: A Bench Top Study of the Optimization of LVAD Cannula Implantation to Reduce Risk of Cerebral Embolism.
Creator: Clark, William, Kassab, Alain, Divo, Eduardo, Ilie, Marcel, University of Central Florida
Abstract / Description: Physical bench top experiments are performed to validate and complement ongoing computational fluid dynamics (CFD) analyses of ventricular assist device (VAD) circulation. VADs are used in patients whose hearts do not function to their maximum potential due advanced stages of heart disease and, consequently, are unable to adequately supply blood to the systemic circulation. VADs are commonly utilized as a bridge-to-transplantation, meaning that they are implanted in patients while waiting for...
Show morePhysical bench top experiments are performed to validate and complement ongoing computational fluid dynamics (CFD) analyses of ventricular assist device (VAD) circulation. VADs are used in patients whose hearts do not function to their maximum potential due advanced stages of heart disease and, consequently, are unable to adequately supply blood to the systemic circulation. VADs are commonly utilized as a bridge-to-transplantation, meaning that they are implanted in patients while waiting for a heart transplant. In such cases of long term utilization of VADs, it has been reported in the literatures that thrombo-embolic cerebral events occur in 14-47% of patients over the period of 6 to 12 months. This is a result of thrombus forming despite the use of anticoagulants and advances in VAD design. Accepting current rates of thrombo-embolisms, the main objective of the project is to identify and propose an optimal surgical cannula implantation orientation aimed at reducing the rate of thrombi reaching the carotid and vertebral arteries and thus reduce the morbidity and mortality rate associated with the long term use of VADs to patients suffering from advanced heart failure. The main focus of the experiment is on the physical aspect using a synthetic anatomically correct model constructed by rapid prototyping of the human aortic arch and surrounding vessels. Three VAD cannula implantation configurations are studied with and without bypass to the left carotid artery or to the Innominate artery with ligation of the branch vessel at its root. A mixture of water and glycerin serves to match blood viscosity measured with a rotating cone-plate viscometer. The Reynolds number in the ascending aorta is matched in the flow model. A closed loop mock circulatory system is then realized. In order to match the Reynolds number in the ascending aorta and LVAD cannula with that of the CFD model, a volumetric flow rate of 2.7 liters per minute is supplied through the synthetic VAD cannula and 0.9 liter per minute is supplied to the ascending aorta. Flow rates are measured using rotary flow meters and a pressure sensor is used to ensure a mean operating pressure of 100 mmHg is maintained. Synthetic acrylic blood clots are injected at the inlet of the VAD cannula and they are captured and counted at the vertebral and carotid arteries. The sizes of the thrombi simulated are 2, 3.5 and 5 mm which are typical of the range of diameters encountered in practice. Nearly 300 particles are released over 5 separate runs for each diameter, and overall embolization rates as well as individual embolization rates are evaluated along with associated confidence levels. The experimental results show consistency between CFD and experiment. Means comparison of thromboembolization rates predicted by CFD and bench-top results using a Z-score statistic with a 95% confidence level results in 22 of 24 cases being statistically equal. This study provides confidence in the predictive capabilities of the bench-top model as a methodology that can be utilized in upcoming studies utilizing patient-specific aortic bed model.
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Date Issued: 2012
Identifier: CFE0004365, ucf:49412
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004365

Title: Dynamics of a Perfectly Premixed Jet Flame Exhibiting Self-Excited High-Frequency, Transverse Thermoacoustic Instabilities.
Creator: Tran, Lucky, Kapat, Jayanta, Kassab, Alain, Vasu Sumathi, Subith, University of Central Florida
Abstract / Description: This work is an investigation of the behavior of a premixed turbulent jet flame in a cylindrical dump combustor. The degeneracy of the simple configuration in this study lends itself for a detailed study of inherent mechanisms of a self-excited thermoacoustic instability in isolation from system coupling effects, enabling detailed numerical simulations to be carried out to supplement experimental findings. Tests were done at a nominal pressure of 8 bar and inlet temperature around 450 ?C....
Show moreThis work is an investigation of the behavior of a premixed turbulent jet flame in a cylindrical dump combustor. The degeneracy of the simple configuration in this study lends itself for a detailed study of inherent mechanisms of a self-excited thermoacoustic instability in isolation from system coupling effects, enabling detailed numerical simulations to be carried out to supplement experimental findings. Tests were done at a nominal pressure of 8 bar and inlet temperature around 450 ?C. Self-excited large eddy simulations were also carried out in OpenFOAM, using a b-? flame-wrinkling model to model the combustion process. Eigenfrequency analysis in COMSOL was also done to support and explain the findings from both the numerical simulations and trends observed in the experiments. Measurements from high frequency pressure transducers were analyzed to determine the frequencies of the excited modes in the rig test and compared to the spectra from the LES simulation. The time-resolved fields from the LES simulation were phase-averaged to deduce the acoustic-flame interactions. Despite the (axis)symmetry in this configuration, the non-axisymmetric 1T and 1T1L modes were (simultaneously) excited. Two distinct behaviors are noted for the dynamic flame behavior. In the downstream region, the flame motion is well described by a bulk kinematic displacement as a result of the interaction of the flame front with the local acoustic perturbation. In the upstream region, near the combustor dump plane, large-scale wrinkles are observed in the flame front that have characteristics of a convective wave. The current findings provide additional evidence supporting and further establishing the theory of inherent acoustic-flame interactions as an excitation mechanism (distinct from acoustically-induced hydrodynamic oscillations) for high-frequency, transverse thermoacoustic instabilities.
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Date Issued: 2019
Identifier: CFE0007542, ucf:52616
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007542

Title: Computational Fluid Dynamics Proof of Concept and Analysis of a Self-Powered Fontan Circulation.
Creator: Ni, Marcus, Kassab, Alain, Divo, Eduardo, Chopra, Manoj, University of Central Florida
Abstract / Description: The Fontan circulation is a result of the last (third stage) surgical procedure to correct a single ventricle congenital cardiac disorder in children. Although the Fontan circulation has been successfully established in surgeries over the years, it is flawed and can lead in certain cases to pre-mature death. The main cause of this failure is due to increased pulmonary vascular resistance due to loss pulse pressure and blood flow. In healthy circulations, the heart pumps directly to the lungs,...
Show moreThe Fontan circulation is a result of the last (third stage) surgical procedure to correct a single ventricle congenital cardiac disorder in children. Although the Fontan circulation has been successfully established in surgeries over the years, it is flawed and can lead in certain cases to pre-mature death. The main cause of this failure is due to increased pulmonary vascular resistance due to loss pulse pressure and blood flow. In healthy circulations, the heart pumps directly to the lungs, where as (")Single Ventricle(") patients must use a single sided heart to supply blood to the rest of the body before the lungs. Improvements to the Fontan circulation have been proposed, but they require extensive care or external devices. We propose a (")Self-Powered(") Fontan circulation that will inject energy into the pulmonary system by adding an injection jet shunt (IJS) directly from the heart. The IJS will provide the pulse pressure, blood flow, and entrainment that the pulmonary vascular system needs to function at a healthy level. The difference between a healthy and sick Fontan circulation is 3-5[mmHg] in the IVC. The goal of the IJS is to cause this 3-5[mmHg] pressure drop in the IVC. In the analysis of the Fontan, ascertaining energy losses due to flow jet impingements and flow mixing is critical. Moreover, in order to better understand surgical alternatives is it important to have a robust multi-scale 0D-3D CFD analysis tool that permits investigation of surgical alternatives in a virtual physics-based environment. To this end, a lumped parameter model (LPM) is tightly coupled at the time step level with a full 3D computational fluid dynamics (CFD) model. Using this model scheme, the Fontan test section is no longer being modeled by the LPM. Therefore, it is not limited by the 0D nature of the vascular resistance, capacitance, and inertia bed model. The CFD can take over at the area of interest which accounts for flow directionality and momentum transfer that the LPM is unable to capture. To efficiently calculate optimal IJS configurations, a closed loop steady state model was created to solve a simplified Fontan circulation in 3D. Three models were created with several different optimized configurations, a synthetic model (average dimensions of 2-4 year-old Fontan patients), and two patient-specific models (10 and 24-year-old). The model configurations include changes in the IJS nozzle diameter and IJS placement along the pulmonary artery. These configurations are compared to a baseline model with no IJS. All three models suggest that the IJS helps to decrease IVC pressure while increasing pulse pressure and blood flow to the pulmonary system.
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Date Issued: 2017
Identifier: CFE0006630, ucf:51303
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006630

Title: Computational Fluid Dynamics Study of Thromboembolism as a Function of Shunt Size and Placement in the Hybrid Norwood Palliative Treatment of Hypoplastic Left Heart Syndrome.
Creator: Seligson, John, Kassab, Alain, DeCampli, William, Mansy, Hansen, University of Central Florida
Abstract / Description: The Hybrid Norwood procedure has emerged as a promising alternative palliative first stage treatment for infants with Hypoplastic Left Heart Syndrome (HLHS). The procedure is done to provide necessary blood flow to the pulmonary and systemic regions of the body. The procedure can affect hemodynamic conditions to be pro-thrombotic, and thrombus particles can form and release from the vessel walls and enter the flow. Assuming these particles are formed and released from the shunt surface, a...
Show moreThe Hybrid Norwood procedure has emerged as a promising alternative palliative first stage treatment for infants with Hypoplastic Left Heart Syndrome (HLHS). The procedure is done to provide necessary blood flow to the pulmonary and systemic regions of the body. The procedure can affect hemodynamic conditions to be pro-thrombotic, and thrombus particles can form and release from the vessel walls and enter the flow. Assuming these particles are formed and released from the shunt surface, a Computational Fluid Dynamics (CFD) model can be used to mimic the patient's vasculature geometry and predict the occurrence of embolization to the carotid or coronary arteries, as well as the other major arteries surrounding the heart. This study used a time dependent, multi-scale CFD analysis on patient-specific geometry to determine the statistical probability of thrombus particles exiting each major artery. The geometries explored were of a nominal and patient specific nature. Cases of 90% and 0% stenosis at the aortic arch were analyzed, including shunt diameters of 3mm, 3.5mm, and 4mm. Three different placements of the shunt were explored as well. The intent of this study was to suggest best methods of surgical planning in the Hybrid Norwood procedure by providing supporting data for optimal stroke and myocardial infarction prevention.
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Date Issued: 2017
Identifier: CFE0006655, ucf:51232
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006655

Title: Combustion of 1,3-Butadiene behind Reflected Shocks.
Creator: Lopez, Joseph, Vasu Sumathi, Subith, Orlovskaya, Nina, Kassab, Alain, University of Central Florida
Abstract / Description: The chemical kinetics of 1,3-butadiene (1,3-C4H6) are important because 1,3-butadiene is a major intermediate during the combustion of real fuels. However, there is only limited information on the chemical kinetics of 1,3-butadiene combustion, which has applications in several combustion schemes that are currently being developed, including spark-assisted homogeneous charge compression ignition and fuel reformate exhaust gas recirculation.In the present work, the ignition delay times of 1,3...
Show moreThe chemical kinetics of 1,3-butadiene (1,3-C4H6) are important because 1,3-butadiene is a major intermediate during the combustion of real fuels. However, there is only limited information on the chemical kinetics of 1,3-butadiene combustion, which has applications in several combustion schemes that are currently being developed, including spark-assisted homogeneous charge compression ignition and fuel reformate exhaust gas recirculation.In the present work, the ignition delay times of 1,3-butadiene mixtures has been investigated using pressure data. Oxidation of 1,3-butadiene/oxygen mixtures diluted in argon or nitrogen at equivalence ratios (?) of 0.3 behind reflected shock waves has been studied at temperatures ranging from 1100 to 1300K and at pressures ranging from 1 to 2atm. Reaction progress was monitored by recording concentration time-histories of 1,3-butadiene and OH* radical at a location 2cm from the end wall of a 13.4m long shock tube with an inner diameter of 14cm. 1,3-Butadiene concentration time-histories were measured by absorption spectroscopy at 10.5?m from the P14 line of a tunable CO2 gas laser. OH* production was measured by recording emission around 306.5nm with a pre-amplified gallium phosphide detector and a bandpass filter. Ignition delay times were also determined from the OH* concentration time-histories. The measured concentration time-histories and ignition delay times were compared with two chemical kinetics models. The measured time-histories and ignition delay times provide targets for the refinement of chemical kinetic models at the studied conditions.
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Date Issued: 2017
Identifier: CFE0006618, ucf:51276
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006618

CFD (8)	+ -
Combustion (7)	+ -
combustion (5)	+ -
heat transfer (5)	+ -
Computational Fluid Dynamics (4)	+ -

LVAD (4)	+ -
computational fluid dynamics (4)	+ -
Finite Element Analysis (3)	+ -
Heat Transfer (3)	+ -
Left Ventricular Assist Device (3)	+ -
Pavlik Harness (3)	+ -
Acoustic (2)	+ -
Anisotropy (2)	+ -
Autorotation (2)	+ -
Developmental (2)	+ -
Developmental Dysplasia of the Hip (2)	+ -
Fluid Structure Interaction (2)	+ -
Fused Deposition Modeling (2)	+ -
Ignition Delay Time (2)	+ -
Inverse Problem (2)	+ -
LPM (2)	+ -
Lean (2)	+ -
Lumper Parameter Model (2)	+ -
Meshless Methods (2)	+ -
Methane (2)	+ -
Modeling (2)	+ -
Optimization (2)	+ -
Parameter Estimation (2)	+ -
Premixed Combustion (2)	+ -
Proper Orthogonal Decomposition (2)	+ -

ETD Collection (86)	+ -
Honors Collection (9)	+ -

Kassab, Alain (95)	+ -
University of Central Florida (95)	+ -
Divo, Eduardo (19)	+ -
Kapat, Jayanta (19)	+ -
Vasu Sumathi, Subith (18)	+ -

Mansy, Hansen (14)	+ -
Bai, Yuanli (8)	+ -
Das, Tuhin (8)	+ -
Chow, Louis (6)	+ -
DeCampli, William (6)	+ -
Moslehy, Faissal (6)	+ -
Ahmed, Kareem (5)	+ -
Gordon, Ali (4)	+ -
Ilegbusi, Olusegun (4)	+ -
Ilie, Marcel (4)	+ -
Simaan, Marwan (4)	+ -
Chopra, Manoj (3)	+ -
Deng, Weiwei (3)	+ -
Gou, Jihua (3)	+ -
Kumar, Ranganathan (3)	+ -
Lin, Kuo-Chi (3)	+ -
Orlovskaya, Nina (3)	+ -
Peles, Yoav (3)	+ -
Qu, Zhihua (3)	+ -
Steward, Robert (3)	+ -
Beggs, Kyle (2)	+ -
Bhattacharya, Samik (2)	+ -
Ceballos, Andres (2)	+ -
Gerace, Salvadore (2)	+ -
Guimond, Stephen (2)	+ -

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