bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy Absorption of Axial Members With the Inclusion of Functionally Graded Cellular Structure
Authors: Ali Muhammad , Alam Khairul , Ohioma Eboreime
Published: March 2016

Axial members are commonly used in automotive structures and are responsible for absorbing significant portion of impact energy in the event of an accident. This study was conducted to investigate the effects of inclusion of functionally graded cellular structures in thin walled members under compressive axial loading. A compact functionally graded cellular structure was introduced inside a 352 mm long square tube with side length and wall thickness of 74 mm and 3.048 mm, respectively. The tube wall material was aluminum. The cellular structure’s geometry was observed in the cross-section of a banana peel that has a specific graded cellular packing in a confined space. This packing enables the peel to protect the internal soft core from external impacts. The same cellular pattern was used to construct the structure in present study. The study was conducted using non-linear finite element analysis in ABAQUS. The hybrid structure (tube and graded cellular structure) was fixed on one side and on the other (free end) side, was struck by a rigid mass of 300 Kg travelling at a velocity of 35 mph (15.64 m/s) along the axis of the square tube and perpendicular to the in-plane direction of the graded cellular structure. The tube and cell walls were discretized using reduced integration, hourglass control, 4 nodes, and hexahedral shell elements. The impact plate was modeled with 4 node rigid shell elements. General contact conditions were applied to define surface interaction among graded structure, square tube, and rigid plate. The parameters governing the energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, and energy curves, were evaluated. The results showed that the inclusion of graded cellular structure increased the energy absorption capacity of the square tube by 41.06%. The graded structure underwent progressive stepwise, layer by layer, crushing mode and provided lateral stability to the square tube thus delaying local tube wall collapse and promoting outward convex localized folds on the tube’s periphery as compared to highly localized and compact deformation modes that are typically observed in an empty square tube under axial compressive loading. The variation in deformation mode, large contact areas, presence of graded cellular structure resulted in enhanced stiffness of the hybrid structure, and therefore, high energy absorption by the structure. The results of this preliminary study show a potential of functionally graded cellular materials to significantly improve the energy absorbing capacities of thin walled members under axial loading by altering member’s crushing deformation modes.
Displacement Amplification Using a Compliant Mechanism for Vibration Energy Harvesting
Authors: Elsisy Moataz , Anis Yasser , Arafa Mustafa , Saleh Chahinaz
Published: March 2016

In this paper, we introduce a symmetric five-bar compliant mechanism for the displacement amplification of mechanical vibration. When the proposed mechanism is connected to an energy harvester, input excitation vibrations to the mechanism are amplified, which leads to an increase in harvested power. The mechanism is composed of both rigid links and flexure hinges, which enable deflection. The flexure hinges we use are either of the right-circular, or the corner-filleted types. The mechanism is analyzed using a pseudo-rigid-body-model, where flexure hinges are substituted with rotational springs. We developed an analytical model of the displacement amplification, which was validated both experimentally and numerically using a finite element model. Our model reveals that the displacement amplification is a function in design parameters, such as the geometry of the mechanism, the flexure hinges stiffness, in addition to the load caused by the harvester. The effects of the flexure hinge dimensions on the flexure hinges stiffness, and thus on displacement amplification were investigated. Preliminary experiments indicate the success of our proposed mechanism in amplifying small excitation harmonic inputs and generation of power.
Numerical and Experimental Investigation of the Flow in the SNS Jet Flow Target
Authors: Barbier Charlotte , Wendel Mark , Felde David , Daugherty Michael C.
Published: March 2016

Computational Fluid Dynamic (CFD) numerical simulations were performed for the flow inside the Spallation Neutron Source jet-flow target vessel at Oak Ridge National Laboratory. Different flow rates and beam conditions were tested to cover all the functioning range of the target, but for brevity, only the nominal case with a mass flow rate of 185 kg/s and a beam power of 1.54MW is presented here. The heat deposition rate from the proton beam was computed using the general-purpose Monte Carlo radiation transport code MCNPX and the commercial CFD code ANSYS-CFX was used to determine the flow velocity in the mercury and the temperature fields in both the mercury and the stainless steel vessel. Boundary conditions, turbulence model and mesh effects are presented in depth. To validate the numerical approach, Particle Imagery Velocimetry (PIV) measurements on a water-loop setup with an acrylic jet-flow target mock-up were performed and compared to the numerical simulations. It was found that a sustained wall jet was developed across the whole length of the vulnerable surface, confirming the good design of the jet-flow target. Overall, good agreements were observed between the experiments and the simulations: the velocity contours and the shape of the recirculation zone near the side baffle are qualitatively similar. However, some differences were also observed that underlines the shortcomings of both the numerical simulations and the experimental measurements.
Multiphase CFD Analysis of a Subsea Intervention System
Authors: Maghsoudi Elham , Godse Uday , Gill Alistair
Published: March 2016

In this study, a computational fluid dynamics (CFD) analysis was conducted to evaluate a new design of an intervention system. A multiphase analysis was performed to understand the mixing characteristics as the cement is pumped into the well and the degree to which the cement could be contaminated with spacer fluid. A transient multiphase analysis was conducted to examine the flow and the mixing behavior through the various sections of the intervention system. A combination of 2D and 3D CFD models was used, depending upon the geometry in each section. The results indicated that the intervention system operates efficiently without diluting the cement. Non-Newtonian methods used in CFD were validated using available theoretical and experimental data. In a large-scale yard test, good agreement was obtained for resin and water; however, cement did not show good agreement as the flow rate increased over 1 bbl/min.
The Influence of Micro Scale Ratchet Depth on the Motion of Leidenfrost Drop
Authors: Ok Jeong Tae , Park Sunggook
Published: March 2016

The influence of ratchet depth on the motion of Leidenfrost water drop was investigated as a continuous effort to reveal the driving mechanism. Continuous directional rebounding behavior of the drop was observed only at below 200°C on both micro ratchets with two different depth-to-period aspect ratios (1:5 and 1:10) and sharp ridges. Overall, the shallow ratchets generated more efficient drop mobility in the entire surface temperature range of 193–299°C due to the increased area between the bottom of the drop and the ratchet surface, caused by the geometrical benefit. However, the depth effect was only critical at relatively lower surface temperatures.
Intelligent Mobility Cane for People Who are Blind and Deaf-Blind: A Multidisciplinary Design Project That Assists People With Disabilities
Authors: Iglesias Victoria Patricia , Behm Gary , Oh Tae
Published: March 2016

Vision loss knows no boundaries; it can affect anyone, of any age, income level, race, or ethnic background, at any time. Regardless of the level of visual impairment, vision loss can impact a person’s life and their ability to complete everyday tasks. One of the greatest challenges that a blind or deaf blind person faces is the ability to navigate safely and independently through the physical world. Traveling with little or no vision at all can be challenged and inaccessible, limiting the ability to work, go to school, take care of personal needs, or socialize with others.

The purpose of this paper is to describe and discuss a multidisciplinary project to design and build a low cost, light weight “Intelligent Mobility Cane” prototype that will aid deaf-blind and blind persons in navigating surroundings via real-time tactile and directional force feedback and guidance. The system is designed for providing information about a physical surrounding environment to a user. The solution developed by the team is a handle that attaches to a white cane and provides directional feedback to the user using a roller assembly. The roller assembly uses four bearings that rotate in one direction or another to indicate the direction the user should move to avoid obstacles. A vibration motor with different patterns of vibration is also embedded in the handle to warn about objects at upfront. The ultra-sonic sensors are used to convey the information of the environment to the handle itself. The finished cane physically resembles a conventional cane therefore allowing the user to still be able to sweep the cane, tap and feel the ground. To evaluate the performance and usability of the designed handle, the authors visited Association of Blind and Visual Impaired Association, where they formed a group of blind and deaf-blind evaluators. The result of the evaluations was positive and several suggestions were shared by the group to improve the cane.
Modeling and Simulations of Transformation and Twinning Induced Plasticity in Advanced High Strength Austenitic Steels
Authors: Khan Rashid , Pervez Tasneem , Al-Abri Omar S.
Published: March 2016

The current research work is focused on the development of a combined micromechanical model of transformation and twinning induced plasticity mechanisms in austenite based high Mn steels. Both mechanisms are combined by incorporating transformation in twinning based crystal plasticity model. Initially, mechanical twinning is incorporated in slip based crystal plasticity model. Afterwards, transformation phenomenon (austenite to martensite) is included in the developed slip and twin based crystal plasticity model. The kinematics of the mechanisms is developed by defining elastic, plastic, and transformation deformation gradients. These deformation gradients are then used to calculate stress tensors. The constitutive equations in terms of integration algorithm are implemented in ABAQUS as a user-defined subroutine. Three dimensional finite element model of single and polycrystal austenite are developed. Single austenite crystal is represented by one finite element while the behavior of polycrystal austenite is estimated through 500 grains. The orientation of each grain is defined through Euler angles. The performance of the model is evaluated through finite element simulations in order to predict the elastic-plastic and transformation behaviors of single and polycrystal austenite under different loading conditions i.e. uniaxial tension and simple shear. The developed model is in good agreement with published literature. In simple shear, prominent difference in stress magnitude is found once twinning mode is incorporated in slip and transformation. This difference has significant magnitude in case of polycrystal austenite. This shows substantial advantage (in terms of strength and formability) of incorporating mechanical twinning along with slip and transformation.
In-Plane Parametric Instability of a Rigid Body With a Dual-Rotor System
Authors: Anilkumar Allen , Kartik V.
Published: March 2016

Rotating machines can be modeled at a basic level using lumped masses that are rotating about and attached using springs to an axis. Even such seemingly simple system can exhibit rich dynamics in the presence of time-varying terms in the governing differential equations. This paper investigates the dynamics of a rigid body with two attached rotors that rotate in the same plane. The system is parametrically-excited and the equations of motion are periodic in both rotor frequencies. The frequency spectra of the time responses show distinct side-band structures centered about the unforced natural frequencies. In addition to classical resonances, the stability diagrams generated using Floquet theory reveal instabilities at unexpected combinations of the forcing and natural frequencies. The harmonic balance method is employed to verify the stability boundaries obtained using Floquet theory. The study reveals safe regimes of parameter combinations that can help prevent the onset of instability in such systems.
Carbon Capture Using Amine-Impregnated Mesoporous Sorbent in Fixed and Bubbling Beds
Authors: Rabha Swapna S. , Panday Rupendranath , Breault Greggory , Gopalan Balaji , Tucker Jonathan , Rogers William
Published: March 2016

Capture of carbon dioxide gas from a flue gas mixture (N2:CO2 = 80:20) using amine-impregnated mesoporous sorbent (NETL-32D) was investigated in a small scale batch unit at ambient temperature and pressure. The variation of local bed temperature at different axial location of the bed, pressure drop across the bed, time to carbon breakthrough and adsorption capacity as a function of moisture content, bed heights and flow rates under both fixed bed and bubbling bed conditions was reported. Further, a time difference between the time to reach the peak bed pressure drop and temperature from the carbon breakthrough was established. The present findings are designed to offer a valuable data set for validation of CFD models studying carbon capture devices.
Neutral Parametric Canonical Form for 2D and 3D Wireframe CAD Geometry
Authors: Freeman Robert S. , Bowman K. Eric , Red Ed , Staves Daniel R.
Published: March 2016

Transferring CAD data between heterogeneous CAD systems is a challenge because of differences in feature representation. A study by the National Institute for Standards and Technology (NIST) performed in 1999 made a conservative estimate that inadequate interoperability in the automotive industry costs them $1 billion per year. One critical part of eliminating the high costs due to poor interoperability is a neutral format between heterogeneous CAD systems. An effective neutral CAD format should include a current-state data store, be associative, include the union of CAD features across an arbitrary number of CAD systems, maintain design history, maintain referential integrity, and support synchronous collaboration. This research has focused on extending an existing synchronous collaborative CAD software tool to allow for a neutral, current-state data store. This has been accomplished by creating a Neutral Parametric Canonical Form (NPCF) which defines the neutral data structure for many basic CAD features to enable translation between heterogeneous CAD systems. The NPCF’s for a few key features have been implemented in a synchronous collaborative program and work between the NX and CATIA CAD systems. The 3D point, 2D point, 2D line, and 2D spline NPCF’s will be specifically presented. Complex models have successfully been modeled and exchanged in real time and have validated the NPCF approach. Multiple users can be in the same part at the same time in different CAD systems and create and update models in real time.
Options to Reduce Net Load Variability in a Campus With Very High Solar Penetration
Authors: Radhakrishnan Shriram , Reddy T. Agami
Published: March 2016

The last decade has seen the increase of solar and wind generation systems which has led to high grid penetration of such technologies. Currently, the issue of grid stability and reliability with increased levels of such non-dispatchable generation is of great fundamental concern. This paper reports on the results of analyzing 15 min monitored data over a whole year from a large university campus with over 50% solar penetration of one of its four sub-stations. Net loads or electric purchases are the differences between the campus electric load and the electricity production of the solar system. These net loads are analyzed both in terms of diurnal “duck curves” and as load duration curves in order to determine the frequency and magnitude of different ramping up and down events experienced during the on-peak and off-peak periods. The extent to which such events can be tempered by installing combined heat and power (CHP) systems is studied, and it is found that increases in levels of net load stability vary non-linearly with size of the installed CHP system. Though the results are specific to this case study, the methodology adopted and some of the results and conclusions reached would be useful to those performing similar evaluations in other parts of the world.
Optimization of Nano Fluid Flow for Micro Channel Heat Sinks With Rectangular Cross-Section
Authors: Kavousi Sepideh , Abbassi Abbas
Published: March 2016

In this paper, three-dimensional Al2O3-water nano fluid flow and heat transfer is optimized numerically. A numerical FORTRAN code based on the finite volume method and SIMPLER algorithm is developed to solve the governing equations. The code is carefully validated by comparing numerical predictions with experimental data. Aspect ratio, number of channels in the heat sink and solid fraction factor are considered as degrees of freedom. The goal is to find out the best possible number of channels in the system, and geometry of each channel that maximizes the global thermal conductance. The results show that the geometric parameters have a strong effect on the performance of micro channel heat sink. Comparison of the results of water and Al2O3-water nano fluid demonstrated that water showed a better thermal performance than nano fluid which indicates that neither Re nor pressure drop along the channel are good parameters to compare the thermal performance of nano fluid and water.
Resistance Welding Process Development and Optimization for Recycled High-Density Polyethylene (HDPE)
Authors: Baumann Peter F. , Sendrowski Lucas
Published: March 2016

Large recycled high-density polyethylene (HDPE) structural members, difficult to manufacture by extrusion processes, have been created by the hot plate welding of simple plastic lumber sections. Hot plate welding generates better joint strength than any other welding method currently employed in plastic manufacturing. However, to achieve the desired temperature of the thick plate to melt the polymer uniformly, the process needs a high amount of heat energy requiring furnace (or resistance) heating of a considerable mass. A new method which could combine the heating element and a thin plate into one source could be more efficient in terms of heat loss and thus energy used. The premise of this investigation is to replace the hot plate with a very thin piece of high resistance nickel-chromium alloy ribbon to localize the application of heat within a plastic weld joint in order to reduce energy loss and its associated costs. This resistance ribbon method uses electrical current to reach an adequate temperature to allow for the welding of the HDPE plastic. The ribbon is only slightly larger than the welding surface and very thin to reduce the loss of excess heat through unused surface area and thick sides.

The purpose of this project was to weld recycled high-density polyethylene (HDPE) using resistance welding and to match the tensile strength results considered acceptable in industry for hot plate welding, that is, equal to or greater than 80% of the base material strength. Information obtained through literature review and previous investigations in our laboratories established welding (heating) temperature and time as testing factors. Designed experimentation considered these factors in optimizing the process to maximize the weld tensile strength. A wide-ranging full-factorial experimental design using many levels was created for the initial testing plan. Tensile strengths obtained after welding under the various condition combinations of weld temperature and time revealed a region of higher strength values in the response surface. After the wide-range initial testing, the two control parameters, heating temperature and heating time, were ultimately set up in a focused Face Centered Cubic (FCC) Response Surface Method (RSM) testing design and the tensile strength response was then analyzed using statistical software. The results obtained indicated a strong correlation between heating time and heating temperature with strength. All welded samples in the final testing set exhibited tensile strength of over 90% base material, meeting the goal requirements. A full quadratic equation relationship for tensile strength as a function of welding time and temperature was developed and the maximum tensile strength was achieved when using 280°C for 60 seconds.
Design of a Recirculating Water Tunnel for the Study of High-Reynolds Number Turbulent Boundary Layers
Authors: Daniel Libin , Mohagheghian Shahrouz , Dunlap Dalton , Ruhlmann Eric , Elbing Brian R.
Published: March 2016

This paper reports on the design and fabrication of a high-Reynolds number recirculating water tunnel, which will be used primarily for the study of turbulent boundary layers with an emphasis on drag reduction applications. The primary design specifications were (i) achieve a momentum thickness based Reynolds number above 10,000, (ii) maximize optical access, and (iii) minimize flow non-uniformity. This paper discusses the design considerations and procedures to meet each of these design criteria as well as the manufacturing of the components, installation, and design of auxiliary systems such as the pressure regulation system. There are several recirculating water tunnels at universities that can achieve comparable Reynolds numbers, but they were either built with at least double the budget of the current project or are refurbished tunnels from other laboratories (i.e. key design considerations were already fixed). Thus, the current work offers a guide for the overall design of a low-cost, high-Reynolds number water tunnel. A brief review of other recirculating high-Reynolds number water tunnels is included. Currently, installation has begun with the fabrication complete.
Preliminary FAA-Hybrid III Spinal Injury Criteria for Oblique-Facing Aircraft Seats
Authors: Humm John , Moorcroft David , Yoganandan Narayan , DeWeese Rick , Taylor Amanda , Pintar Frank
Published: March 2016

Occupant injury potential to oblique loading at aircraft crash severities is unknown. The objective of the present study was to derive preliminary injury criteria for the Federal Aviation Administration (FAA) Hybrid III anthropomorphic test device (ATD) under oblique loading conditions. Twelve sled tests were conducted at four pulse severities and three configurations. An acceleration pulse representative of the one specified in Title 14 Code of Federal Regulations Part 25.562, emergency landing dynamic condition for horizontal impact was used as an input. Pulses were scaled in magnitude at 50, 61, 75 and 100% of the peak acceleration 13.7, 10.2, 8.6 and 6.8 m/s, respectively. The three conditions were: 45-degrees, no arm rest, pelvis restrained with two belts, legs restrained; 45-degrees, with arm rest, single lap belt, legs restrained; 30-degrees, no arm rest, two lap belts, legs unrestrained. The ATD was placed on a generic seat representative of aircraft seat geometry and the seat was oriented obliquely. ATD accelerations, thoracic and lumbar spine forces, and restraint forces were recorded. Peak tension forces in the thoracic and lumbar spine ranged from 10–12.7 kN at the highest pulse to 3.6–4.2 kN at the lowest pulse. Previously reported in-house post mortem human surrogate (PMHS) tests provided a matched-paired dataset for combining injuries with ATD metrics. From this limited sample set, 5.2 kN tension force in the spine is suggested for the FAA-Hybrid III ATD as a preliminary injury criteria in oblique loading in the aviation environment.
Shear Effects on Phase Inversion in Oil-Water Flow
Authors: Zhang Mo , Wang Shoubo , Mohan Ram S. , Shoham Ovadia , Gao Haijing
Published: March 2016

Oil-water dispersed flow, in which one of the phases either water or oil is dispersed into the other phase, which is the continuous phase, occurs commonly in Petroleum Industry during the production and transportation of crudes. Phase inversion occurs when the dispersed phase grows into the continuous phase and the continuous phase becomes the dispersed phase caused by changes in the composition, interfacial properties and other factors. Production equipment, such as pumps and chokes, generate shear in oil-water mixture flow, which has a strong effect on phase inversion phenomena. In this study, based on the newly acquired data on a gear pump, the relationship between phase inversion region and shear intensity are discussed and the limitation of current phase inversion prediction model is presented.
Optimization of Stationary Flat-Plate Solar Collectors
Authors: Rao Singiresu S.
Published: March 2016

The optimum design of stationary flat-plate solar collectors is considered using the game theory approach for multiple objectives. The clear day solar beam radiation and diffuse radiation at the location of the solar collector are estimated. Three objectives are considered in the optimization problem formulation: maximization of the annual average incident solar energy, maximization of the lowest month incident solar energy and minimization of the cost. The game theory solution represents the best compromise in terms of the supercriterion selected. Because some design parameters such as solar constant, altitude, typical day of each month and most of the design variables are not precisely known, a probabilistic approach is also proposed in this work. The results obtained by the determinist and probabilistic approaches are compared. It is found that the absolute value of each objective function decreases with an increase in either the probability of constraint satisfaction or the coefficient of variation of the random variables. This work represents the first work aimed at the application of multi-objective optimization strategy, particularly the game theory approach, for the solution of the solar collector design problem.
Theoretical Range and Trajectory of a Water Jet
Authors: Trettel Ben , Ezekoye Ofodike A.
Published: March 2016

The trajectory of a water jet is important in many applications, including fire protection, irrigation, and decorative fountains. Increasing the maximum distance the jet travels by changing the nozzle or other variables is often desirable. This distance could be the horizontal range (also often called the reach or throw) or the maximum vertical height. Which factors control the trajectory are unclear. Consequently, a simple analytical model is developed which provides a qualitative understanding of the system. This model differs significantly from previous models. Previous models either used a dragless trajectory, which is correct according to potential flow theory if the jet does not break into droplets, or treated the trajectory as if droplets formed immediately upon leaving the nozzle. Both approaches have been noted to be unsatisfactory by past researchers. Our model compares favorably against available experimental data. Using our model, we show that the range decreases as the nozzle Froude number increases and that range increases as breakup length and droplet size increase.
Application-Based Methodology for Assessment of Flow Boiling Correlations in Microfin Tubes
Authors: Merchant Reem , Mehendale Sunil S.
Published: March 2016

The high flow boiling heat transfer coefficients (HTCs) and comparatively low pressure drop of microfin tubes make them suited to meet the ever-increasing energy efficiencies and burgeoning raw material costs of HVAC & R systems. Since the late 1980s, many empirical or semi-empirical correlations have been proposed to predict the in-tube boiling HTC for microfin tubes. A vast number of experimental studies have also been published for microfin tubes under different operating conditions with different refrigerants. However, due to the complex behavior of two-phase flows, it has been observed that no single correlation can predict the flow boiling HTC reasonably for the entire spectrum of geometric and operating parameters.

The objective of the current study is to develop and provide researchers and practicing engineers with a predictive tool that will help them select the most accurate flow boiling HTC correlation for any practical HVAC & R application. Six popular and widely used correlations have been selected for investigation, which include Yu et al. [1], Thome et al. (as cited in [2]), Cavallini et al. [3], Yun et al. [4], and Chamra and Mago [5] and Wu et al. [6]. Each correlation has been carefully and critically assessed to discover its strengths, weaknesses and applicability to practical situations. In general, for tubes with root diameters greater than 5 mm, Thome et al. [2] and Cavallini et al. [3] predict the flow boiling HTC very well for CO2 and halogenated refrigerants respectively. For tubes with root diameters less than 5 mm, Wu et al. [6] is recommended. However, these recommendations can and do change with an alteration in flow or geometric parameters. Hence a tool is needed to measure the applicability of these correlations. The extensive experimental database collected for this research includes 1636 data points taken from 22 published articles. This wide-ranging database contains experimental points that incorporate all of the geometric and operating conditions that are used in the air-conditioning industry today. Traditionally, experimentation has been the principal means of ascertaining the HTC of microfin tubes. However, such testing is very costly and time consuming. The innovative numerical methodology developed in this work provides the practitioner with a tool to quantify the performance of a correlation for a specific application. This approach has been tested by the authors for several experimental points that span the entire range of real-world geometric and operating parameters. The use of this novel numerical procedure will save the HVAC & R industry significant experimental time and cost.
Magnesium Oxide Based PLGA/Chitosan Microparticles for Controlled Release Study
Authors: Rahman Shekh , Bhattarai Narayan
Published: March 2016

The performance of a therapeutic drug can be optimized by controlling the rate and extent of its release in the body. Polymeric microparticles are ideal vehicles for many controlled release drug delivery applications. Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable, biocompatible and FDA approved synthetic polymer. When PLGA based controlled release drug delivery devices are fabricated, the surface of PLGA is typically modified by other hydrophilic polymers. But some hydrophilic polymers, such as poly(ethylene glycol) (PEG) can negatively influence the therapeutic outcomes. The goal of the present study was to fabricate and investigate the PLGA/chitosan microparticles for controlled release of therapeutic drugs. Chitosan is a naturally occurring biodegradable polysaccharide. We hypothesized that chitosan could be used as a surface coating of PLGA to improve controlled release of therapeutic drugs. The double emulsion solvent evaporation technique was modified and utilized to fabricate the PLGA/chitosan microparticles. The microparticles were tested with respect to several physicochemical properties, such as morphology, size distribution, chemical structure, quantification of chitosan content and in vitro release study of model drug. Magnesium is an essential electrolyte in the human body. Magnesium oxide (MgO) is used for treatment of magnesium deficiency. MgO was encapsulated in the PLGA/chitosan microparticles as a model drug.
Neutron Imaging of a Two-Phase Refrigerant Flow
Authors: Geoghegan Patrick , Sharma Vishaldeep
Published: March 2016

Void fraction remains a crucial parameter in understanding and characterizing two-phase flow. It appears as a key variable in both heat transfer and pressure drop correlations of two-phase flows, from the macro to micro-channel scale. Void fraction estimation dictates the sizing of both evaporating and condensing phase change heat exchangers, for example. In order to measure void fraction some invasive approach is necessary. Typically, visualization is achieved either downstream of the test section or on top by machining to expose the channel. Both approaches can lead to inaccuracies. The former assumes the flow will not be affected moving from the heat exchanger surface to the transparent section. The latter distorts the heat flow path.

Neutron Imaging can provide a non-invasive measurement because metals such as Aluminum are essentially transparent to neutrons. Hence, if a refrigerant is selected that provides suitable neutron attenuation; steady-state void fraction measurements in two-phase flow are attainable in-situ without disturbing the fluid flow or heat flow path.

Neutron Imaging has been used in the past to qualitatively describe the flow in heat exchangers in terms of maldistributions without providing void fraction data. This work is distinguished from previous efforts because the heat exchanger has been designed and the refrigerant selected to avail of neutron imaging.

This work describes the experimental flow loop that enables a boiling two-phase flow; the heat exchanger test section and downstream transparent section are described. The flow loop controls the degree of subcooling and the refrigerant flowrate. Heating cartridges embedded in the test section are employed to control the heat input. Neutron-imaged steady-state void fraction measurements are captured and compared to representative high-speed videography captured at the visualization section. This allows a qualitative comparison between neutron imaged and traditional techniques. The measurements are also compared to correlations in the literature.

Preliminary void fraction images from a macro-channel flow are presented, consisting of 1 channel, 4mm wide, 4mm high and 83.32mm long. Flow regime identification is examined.

The experiments were conducted at the High Flux Isotope Reactor (HFIR) Cold Guide 1D neutron imaging facility at Oak Ridge National Laboratory, Oak Ridge, TN, USA.
A Practical Algorithmic Approach Towards Multi-Modal Resource Constrained Multi-Project Scheduling Problems (MMRCMPSP)
Authors: Völker Michael , Zahid Taiba , Schmidt Thorsten
Published: March 2016

The literature concerning resource constrained project scheduling problems (RCPSP) are mainly based on series or parallel schedule generation schemes with priority sequencing rules to resolve conflicts. Recently, these models have been extended for scheduling multi-modal RCPSP (MMRCPSP) where each activity has multiple possibilities to be performed thus providing decision managers a useful tool for manipulating resources and activities. Nonetheless, this further complicates the scheduling problem inflicted by increase of decision variables. Multiple heuristics have been proposed for this NP-hard problem. The main solution strategy adopted by such heuristics is a two loops decision strategy. Basically the problem is split between two parts where first part is conversion of MMRCPSP to RCPSP (mode fix) while second is finding feasible solution for a resource constrained project and is restricted to single project environments. This research aims on the development of scheduling heuristics, exploring the possibilities of scheduling MMRCPSP with parallel assignment of modes while sequencing the activities. The work addresses Multi-Mode Resource Constrained Multi-Project Scheduling Problem, (MMRCMPSP) by formulating a mathematical model that regards practical requirements of working systems. The algorithm is made intelligent and flexible in order to adopt and shift among various defined heuristic rules under different objectives to function as a decision support tool for managers.
A Knowledge-Based Approach for Supporting Aquaculture Data Analysis Proficiency
Authors: Oliveira Pedro , Costa Ruben , Lima Jose , Ferreira Fernando , Sarraipa Joao
Published: March 2016

European aquaculture companies have business objectives that they cannot achieve due to lack of instruments that would enable them to manage and access such global knowledge and big data, in a multilingual, multi-sector and cross-border setting. A technological approach able to manage data from many companies, which will generate knowledge, will be of maximum usefulness for the aquaculture sector. The companies will be able to transform data into knowledge and use this knowledge to improve efficiency, increase profitability and do business in a sustainable, environmentally friendly way. To support this, the solution will use data mining practices and tools as a cloud service that will be specifically designed for the aquaculture sector, which will be accessible by all the fish farming community. In order to allow even small companies to explore their data and improve in terms of use of feed, environmental impact, growth of the fish, cost, etc. The work presented here, is still part of on-going work currently addressed under the EU AquaSmart project. Results achieved so far do not address the final conclusions of the project but form the basis for the formalization of the AquaSmart domain knowledge along with the Aquaculture Open Data Cloud.
Transient Interface Shape and Deposition Profile Left by Desiccation of Colloidal Droplets on Multiple Surfaces
Authors: Dunning Peter D. , Greyson Marcette , Schertzer Michael J.
Published: March 2016

Control of deposition patterns left by desiccated colloidal droplets is valuable in applications ranging from medical diagnostics to inkjet printing. This investigation presents an experimental method to monitor the transient interface shape of a colloidal droplet during desiccation and to quantify the deposition pattern left by the colloidal material optically. Transient image profiles and particle deposition patterns are examined for droplets containing fluorescent particles that were desiccated on glass and on the photoresist SU-8 3005. Contact line pinning was more prevalent on glass, where the contact diameter remained approximately constant throughout the process and the contact angle decreased with time. On SU-8, the contact diameter was initially constant, but decreased after the contact angle was reduced. The initial contact diameter on glass was similar to the diameter of the deposition pattern. The diameter of the deposition pattern on SU-8 was approximately half of the initial contact diameter. The deposition on SU-8 was also observed to be more uniform than that left on glass. These results suggest that selection of an appropriate substrate is an important consideration for colloidal deposition. The method presented will be used to in future investigations to characterize the effectiveness of coffee stain suppression through the application of external electric fields.
Effect of Longitudinal Vortex Generator Location on Thermoelectric-Hydraulic Performance of a Single Stage Integrated Thermoelectric Power Generator
Authors: Deshpande Samruddhi , Ravi Bharath Viswanath , Pandit Jaideep , Ma Ting , Huxtable Scott , Ekkad Srinath
Published: March 2016

Vortex generators have been widely used to enhance heat transfer in various heat exchangers. Out of the two types of vortex generators: Transverse vortex generators (TVGs) and longitudinal vortex generators (LVGs), LVGs have been found to show better heat transfer performance. Past studies have shown that the implementation of these LVGs can be used to improve heat transfer in thermoelectric generator systems. Here a built in module in COMSOL Multiphysics® was used to study the influence of the location of LVGs in the channel on the comprehensive performance of an integrated thermoelectric device (ITED). The physical model under consideration consists of a copper interconnector sandwiched between p-type and n-type semiconductors and a flow channel for hot fluid in the center of the interconnector. Four pairs of, LVGs are mounted symmetrically on the top and bottom surfaces of the flow channel. Thus, using numerical methods, the thermo-electric-hydraulic performance of the ITED with a single module is examined. By fixing the material size D, the fluid inlet temperature Tin, and attack angle β; the effects of the location of LVGs and Reynolds number were investigated on the heat transfer performance, power output, pressure drop and thermal conversion efficiency. The location of LVGs did not have significant effect on the performance of TEGs in the given model. However, the performance parameters show a considerable change with Reynold’s number and best performance is obtained at Reynold number of Re = 500.
Energy Harvesting Using Galvanically Synthesized Piezoelectric ZnO Nanorods on Flexible Polymer Film
Authors: Oshman Christopher , Chauvin Julie , Opoku Charles , Dahiya Abhishek S. , Alquier Daniel , Lethiecq Marc , Camara Nicolas , Poulin-Vittrant Guylaine
Published: March 2016

This paper reports advancement in bringing flexible piezoelectric nanogenerators (NGs) closer to being realized in a commercial market. We have adopted a method to synthesize piezoelectric ZnO nanorods (NRs) on any electrically conductive surface without a seed layer or a specially selected substrate with matching lattice spacing. By contacting a metal with a dissimilar electro-negativity, a galvanic cell is created in the electrolyte growth medium. We have demonstrated the performance of the as grown NRs on a thin NG using common PET film. The device produced voltages in excess of three times higher than a parallel fabricated reference sample under bending loads.
Dynamics and Stability of a Travelling String Subjected to an Axial Follower Force
Authors: Lad Pranav , Kartik V.
Published: March 2016

The transverse vibrations of an axially moving string are investigated when it is subjected to a distributed axial follower force. The key characteristic of such a force is that it is, at every location, always oriented parallel to the instantaneous slope of the string at that location. First, the equation of motion governing the transverse vibration under the action of such an axial distributed follower force is derived. The model accounts for the effects of both time-varying travelling speed and axial variation in the string’s tension. The stable and unstable regimes due to parametric excitation are obtained using Floquet analysis and compared with a commonly-used model. The effect of the follower force on stability is investigated. The forced response of the string that is moving at constant speed is obtained where the excitation arises due to transverse oscillations of the support(s).
A Comparison of Rate-Controlled Constrained-Equilibrium Formulations
Authors: Hadi Fatemeh , Janbozorgi Mohammad , Sheikhi M. Reza H.
Published: March 2016

In this study, constraint potential and constraint forms of the Rate-Controlled Constrained-Equilibrium (RCCE) method have been investigated in terms of accuracy and performance. Although the two formulations are equivalent mathematically, they show quite different performances from the computational standpoint. The main objective of this work is to determine the most efficient implementation of RCCE to be used in turbulent combustion simulations. Simulations are conducted of an adiabatic, isobaric stirred reactor. The kinetics includes methane oxygen combustion using 133 reaction steps and 29 species. RCCE calculations are performed by 12 constraints. The simulations are carried out over a wide range of initial temperatures for stoichiometric gas mixtures. Performance studies of the two RCCE formulations are carried out and the results are compared with those obtained by direct integration of detailed kinetics.
Separation of Radiative and Convective Wall Heat Fluxes Using Thermal Infrared Measurements Applied to Flame Impingement
Authors: Gomez-Ramirez David , Ekkad Srinath V. , Lattimer Brian Y. , Moon Hee-Koo , Kim Yong , Srinivasan Ram
Published: March 2016

Flame impingement is critical for the processing and energy industries. The high heat transfer rates obtained with impinging flames are relevant in metal flame cutting, welding, and brazing; in fire research to understand the effects of flames on the structures of buildings; and in the design of high temperature combustion systems. Most of the studies on flame impingement are limited to surfaces perpendicular to the flame, and measurements are often performed using heat flux sensors (such as Schmidt-Boelter heat flux transducers) at discrete locations along the target surface. The use of in-situ probes provides high accuracy but heavily limits the spatial resolution of the measurement. Moreover, flame radiation effects are often neglected, due to the small contribution in non-luminous flames, and the entire heat flux to the target is assumed to be due to convection. Depending on the character of the flame and the impingement surface, local radiative heat transfer can be significant, and the contribution of radiation effects has not been fully quantified.

This study presents a novel non-intrusive method with high spatial resolution to simultaneously determine the convective and radiative heat fluxes at a wall interacting with a flame or other high temperature environment. Two initial proof of concept experiments were conducted to evaluate the viability of the technique: one consisting of a flame impinging normal to a target and another with a flame parallel to the target surface. Application of the methodology to the former case yielded a stagnation convective heat flux in the order of 106kWm−2 that decreased radially away from the stagnation point. The radiation field for the direct impingement case accounted on average for 4.4% of the overall mean heat flux. The latter experiment exemplified a case with low convective heat fluxes, which was correctly predicted by the measurement. The radiative heat fluxes were consistent between the parallel and perpendicular cases.
Three Dimensional Single-Walled Carbon Nanotube Foams for Ultrahigh Energy Density Lithium Air Battery Cathodes
Authors: Carter Rachel , Oakes Landon , Pint Cary L.
Published: March 2016

This paper highlights our progress in developing pristine single-walled carbon nanotubes (SWCNTs) into functional materials for lightweight, conductive cathodes in lithium air (Li-air) batteries. We outline a process to produce foams of single-walled carbon nanotubes using liquid processing routes that are free of additives or surfactants, using polar solvents and electrophoretic deposition. To accomplish this, SWCNTs are deposited onto sacrificial metal foam templates, and the metal foam is removed to yield a freestanding, all-SWCNT foam material. We couple this material into a cathode for a Li-air battery and demonstrate excellent performance that includes first discharge capacity over 8200 mAh/g, and specific energy density of ∼ 21.2 kWh/kg (carbon) and ∼ 3.3 kWh/kg (full cell). We further compare this to the performance of foams prepared with SWCNTs that are dispersed with surfactant, and our results indicate that surfactant residues completely inhibit the nucleation of stable lithium peroxide materials — a result measured across multiple devices. Comparing to multi-walled carbon nanotubes produced using the same technique indicates a discharge capacity of only ∼ 1500 mAh/g, which is over 5X lower than SWCNTs in the same processing technique and material architecture. Overall, this work highlights SWCNT materials in the absence of impurities introduced during experimental processing as a lightweight and high performance electrode material for lithium-air batteries.