bluuebunny/crossref_metadata_2025 huggingface dataset:
A Parallelized Generalized Method of Cells Framework for Multiscale Studies of Composite Materials
Authors: Rai Ashwin , Skinner Travis , Chattopadhyay Aditi
Published: January 2020

This paper presents a parallelized framework for a multi-scale material analysis method called the generalized method of cells (GMC) model which can be used to effectively homogenize or localize material properties over two different length scales. Parallelization is utlized at two instances: (a) for the solution of the governing linear equations, and (b) for the local analysis of each subcell. The governing linear equation is solved parallely using a parallel form of the Gaussian substitution method, and the subsequent local subcell analysis is performed parallely using a domain decomposition method wherein the lower length scale subcells are equally divided over available processors. The parellization algorithm takes advantage of a single program multiple data (SPMD) distributed memory architecture using the Message Passing Interface (MPI) standard, which permits scaling up of the analysis algorithm to any number of processors on a computing cluster. Results show significant decrease in solution time for the parallelized algorithm compared to serial algorithms, especially for denser microscale meshes. The consequent speed-up in processing time permits the analysis of complex length scale dependent phenomenon, nonlinear analysis, and uncertainty studies with multiscale effects which would otherwise be prohibitively expensive.
Fabrication, Modeling, and Testing of a Miniaturized Fast Neutron Detector
Authors: Oxandale Samuel W. , Stegeman Luke A. , Hieber Tyler J. , Sarkar Dipta , Bellinger Steven L. , Bahadori Amir A. , Leseman Zayd C.
Published: January 2020

This work outlines the positive-intrinsic-negative diode fabrication process for a Miniaturized Fast Neutron Detector and documents alpha source testing of a single positive-intrinsic-negative diode. The Miniaturized Fast Neutron Detector provides information about the kinetic energy distribution of neutrons with resolution up to 20 MeV and has 1–2% of the volume of comparable current state-of-the-art neutron spectrometers, namely Bonner Ball Neutron Detector sets and Capture-Gated Neutron Scintillator Detectors. The Miniaturized Fast Neutron Detector can be used to estimate neutron doses for heavy charged particle therapy patients improving the understanding of secondary cancer risks, monitor secondary neutron radiation more efficiently in therapy treatment facilities, and perform an important role in protecting astronauts from radiation.
Effects of Plate Curvature on Thermo-Mechanical Performance of U-10Mo Monolithic Fuel Plates
Authors: Ozaltun Hakan , Roh Hee Seok , Mohamed Walid
Published: January 2020

Monolithic fuel is a candidate fuel form being considered for the conversion of high-performance research reactors. This plate-type fuel consists of a high-density, U-Mo fuel in a monolithic form that is sandwiched between zirconium diffusion barriers, and encapsulated in an aluminum cladding. To date, large number of plates have been irradiated with satisfactory performance. The program is now moving into the qualification phase, a predecessor to the timely conversion of the target reactors. Since each reactor employs distinct fuel plate geometries for various consideration, resulting nearly 50 distinct plate geometries with unique plate design features, a single “generic” plate geometry capturing all of the extremities is not achievable. This limitation consequently requires much more cautious performance evaluations, as thermal and mechanical response of a plate with certain geometry may not be representative for a plate with a different geometry. To evaluate the performance of the plates for various geometric parameters, parametric sensitives studies have been employed. One of the important geometric parameters may have potential effects on the performance is the plate curvature. In this study, curved-plates were parametrically simulated to investigate if this geometric parameter has any effects on overall performance, In particular, radius of curvatures of the plates were varied between the bounding values, and the plates were simulated for comparable irradiation histories. The resulted temperature, deformation, stress-strain results were comparatively evaluated. The results have indicated that preferential deformations occur. This consequently caused shifting of plate centerline on curved plates. The magnitude of centerline shifts increased with increasing plate curvatures.
An Experimental Investigation of the Contribution of Different Carbonaceous Nanomaterials to Thermal Conductance of Thermal Interface Materials
Authors: Singh Prashant , Lee Seul-Yi , Mahajan Roop L.
Published: January 2020

With the increasing demand for higher performance and progressive miniaturization of electronic packages, power densities and the attendant thermal dissipation requirements are expected to escalate. One of the important strategies to ensure reliable operation at the device and die (chip) levels is the use of Thermal Interface Materials (TIMs) to reduce the thermal resistance between the chip and the heat sink. In this study, we have carried out an experimental investigation to characterize thermal conductance of TIMs composed of commercially available graphene (c-rGO), graphene nanoplatlets (GNPs) of different lateral sizes (5, 15 and 25 μm), and our in-house produced thermally reduced graphene oxide at 600°C (T-rGO-600). These additives were loaded in a silicone rubber matrix where their loading fraction was fixed at 2% by weight. Thermal conductance of the resulting TIMs was determined by measuring heat flow, in steady state, through a TIM sandwiched between two metal blocks. The thermal conductance values representing the combined resistance of the composite material and the contact resistances between the TIM and the metal blocks were measured at different heat flux levels across the TIM. The results show that the thermal conductance values were independent of the heat load across the TIM as well as the TIM temperature. Further, a detailed investigation of the surface functionality and structural properties has revealed that the in-house produced T-rGO-600 has superior thermal conductance when compared to the above-mentioned carbonaceous nanomaterials, which are considered as potential candidates for enhancing thermal performance of TIMs. The data demonstrates that this result is attributable to the formation of the surface functional groups and the associated morphological changes during the reduction of graphene oxide to the T-rGO-600. Among the different GNPs tested, the GNP-15 exhibited superior thermal performance compared to the GNP-5 and GNP-25 samples.
FDM 3D-Printed Thermoplastic Elastomers: Experiments, Modeling, and Influence of Process Parameters on Properties
Authors: Hripko Brad , Hoover Luke , Damodara Priyadarsini , Reissman Timothy , Lowe Robert
Published: January 2020

Soft, ultra-stretchable thermoplastic elastomers have recently became available for use with desktop, fused deposition modeling printers. However, the effects of additive manufacturing process parameters on final mechanical properties are presently not well-known for this class of materials, making predictive modeling and product design difficult. Here we perform a design of experiments investigation of an elastomeric material that the manufacturer claims to have up to 580% strain at fracture. Within the investigation, two factors, extrusion temperature and layer height, are selected as independent variables and mechanical properties are extracted as dependent variables based on quasi-static tension tests following ASTM D412. Primary statistical results, based on an Analysis of Variance, indicate that hotter extrusion temperatures exhibit higher Young’s moduli (at small strain), lower ultimate tensile strength, and higher fracture strain. Further, the layer thickness is not a factor unless evaluating performance at small strain, in which case it is significant and thicker layers will yield higher Young’s moduli. Several popular hyperelastic constitutive models are calibrated to our tensile data, and a preliminary finite-element simulation of a soft prosthetic finger is performed to demonstrate the potential role of predictive simulations in 3D-printed product design.
Experimental Study of Forced Convection Heat Transfer and Flow Friction of a Water-Cooled Inter-Connected Mini-Channel Heat Sink
Authors: Tikadar Amitav , K. Oudah Saad , Abdulrazzaq Nabeel M. , Paul Titan C. , Khan Jamil A.
Published: January 2020

Experimental investigations were performed to quantify the thermal and hydraulic performances of an inter-connected counter flow mini-channel heat sink under laminar flow regime. The aspect ratio (height/width) and the hydraulic diameter of the mini-channel were 0.33 and 750 μm respectively. Water was used as the working fluid, and a constant heat flux of 120000 W/m2 was applied on the bottom surface of the heat sink. To enable transverse flow between two counter flow streams by utilizing pressure difference, two inter-connectors were made on the middle wall. The height and width of both inter-connectors were the same as the mini-channel. Bottom surface temperature, Nusselt number (Nu), thermal resistance, and friction factor were calculated to address the effect of the inter-connectors on the overall thermal-hydraulic performance of the heat sink. The results showed that at low Reynolds number (Re), inter-connectors affect the heat transfer performance adversely while substantial heat transfer augmentation was achieved at high Re. Additionally, for all of the test range, a significant reduction of friction factor was achieved by employing transverse flow.
Miniature Hemispherical Bowl-Shaped Forming Using SLA Punch and Die: Modeling and Experimental Analysis
Authors: Mondal Debabrata , Morris Jeffrey David , Zhang Bin , Meng Wen , Chakravarty Uttam , Herrington Paul , Schilling Paul
Published: January 2020

Forming processes are a convenient means for bulk production of parts. These parts are used in a wide range of applications from automotive industries to micro-devices in bioengineering. Manufactured parts are required to be precise in their final dimension, and since the billet material undergoes significant plastic deformation during forming, billet material characterization and prediction of final form is essential. In this study, miniaturized bowl-shaped samples of 3003-H14 aluminum alloy were formed using a die and punch manufactured using the stereolithography (SLA) additive manufacturing method. Tensile testing was performed in order to characterize the material properties of the SLA resin. Using the SLA-created die and punch, hemispherical bowl-shaped forms were generated. In order to investigate possible small size effects, experimental load versus displacement results were obtained for billet plate thicknesses of 0.4–0.8 mm. A numerical finite element model was developed to predict the required punch load to manufacture various thickness bowl-shaped forms. A comparison was made between the load verses displacement curves for the different thicknesses, and the numerical model was validated by the experimental results. The validated computational model can then be used to predict the process parameters prior to starting bulk production. Finally, a model with grains was developed and simulated to show the virtual microstructural morphology of the circular plates before and after the forming operation.
Measurement Errors and Uncertainty Estimation of an Experimental Set Up Using a 2D PIV Technique
Authors: Barbosa Flávia V. , Costa Carlos A. P. , Teixeira Senhorinha F. C. F. , Teixeira José C. F.
Published: January 2020

The study of the flow interaction and the heat transfer between air jets and a surface is of paramount importance in industrial processes that apply multiple air jet impingement. To ensure a good performance of the process, high heat transfer rates and uniformization of the flow over the target plate are required. To perform this analysis, a PIV technique was implemented for the measurement of the velocity fields of the flow. However, as any real experiment, the values recorded by the PIV method are subjected to several errors that compromise the reliability and accuracy of the measurements. These errors can have different sources, from the installation and alignment to the particles seeding and calibration procedure. To determine an interval that contains the measurement error, the uncertainty quantification is crucial. In that sense, this paper focus on the identification of measurement errors and uncertainty quantification of an experimental set up specially built for the analysis of the interaction between a non-isothermal jets and non-flat surfaces moving perpendicularly to the jet axis. To ensure the reliability of the results, preliminary tests were performed to guarantee a uniform and stable flow and to determine the range and conditions of operation. In addition, this work presents an analysis of the system, and the source of errors are identified, quantified and, when possible, corrected. The particle seeding, which consists of olive oil droplets, is characterized and its efficiency for the flow tracking is analysed. The test facility was tested to fully characterize the flow field in terms of mean velocity profile and turbulence intensity over a wide range of Reynolds numbers and temperature. Several velocity fields are then measured until convergence of the flow quantities is reached. The combination of these measurements with high spatial resolution and low measurement errors allow to obtain accurate and precise measurement values.
Low-Cost Measurement Technique of Poisson’s Ratio of Thin, Solvent-Sensitive Polymer Membranes
Authors: Dienemann Lara L. , Saigal Anil , Zimmerman Michael A.
Published: January 2020

This paper investigates a low-cost testing procedure that measures Poisson’s ratio of thin membranes whose properties may be affected by traditional speckle patterns which are solvent-based. The shear modulus, a key indicator of how materials will fail — especially for thin membranes subjected to interfacial stresses — is a function of Young’s modulus and Poisson’s ratio, which can be determined by tensile testing.

The precision of using Digital Image Correlation (DIC) to measure Poisson’s ratio coupled with a solvent-free speckle pattern of fused silica on polyimide film specimen is investigated. DIC processes for thin membranes are currently under development. As such, spraying a conventional speckle pattern may be unfeasible for thin polymer membranes whose properties are a function of solvent content. Experimental factors’ effects, such as vibration and area to which DIC is applied, were also studied in a design of experiments. It was determined that using fused silica as a solvent-free speckle pattern, as opposed to a traditional solvent pattern, does not significantly affect the measurements of Poisson’s Ratio of the polyimide film. Furthermore, it was found that the experimental factors noted above can play a significant role in fused silica-speckled Poisson’s ratio specimen.
Peltier Cooling for Low Concentration Photovoltaic Cells: Numerical Modeling and Feasibility Study
Authors: Pant Anuj , Dhole Sourabh , Najafi Hamidreza
Published: January 2020

Thermal management of concentrating photovoltaic (CPV) panels is known as a major concern that has been investigated in the recent years. Appropriate cooling techniques must be employed to maintain optimum cell temperature, thus improving system efficiency and life cycle. Thermoelectric cooling offers several attractive characteristics including high controllability, no need to refrigerant, modularity, quiet operation and more. In this paper, the possibility of using convective cooling using a water channel along with thermoelectric cooling for a low concentration photovoltaic (LCPV) module is investigated. A numerical model is developed using COMSOL Multiphysics® and MATLAB® to assess the performance of a novel CPV-TE system. The proposed system consists of a Thermoelectric cooling (TEC) module attached to the backside of a photovoltaic (PV) cell. A water channel has been implemented on the backside of the Peltier module to provide effective heat removal using water flow. A parametric study is conducted on the proposed system by varying solar concentration incident on the PV, input current to the Peltier cooler and inlet velocity and temperature of the water flow. The temperature distribution through the system, power output from the PV module and energy consumption by the Peltier module are determined under different operational circumstances. The results are extensively discussed to provide an understanding regarding the feasibility of the proposed system.
Data-Driven Decisions in Prototyping and Product Development: A Framework for Uncertainty and Decision-Making
Authors: Ali Hadi , Lande Micah
Published: January 2020

We propose a framework, established in the literature on uncertainty and decision-making, that guides the development of effective prototypes that inform the design of products and systems in a way where digital, big-data become central to the design process. Ultimately, we seek to move design thinking to the new domain of digitization of organizations and product platforms so that the gap between data-driven decisions and creative solutions is bridged through design thinking.
A New Approach to the Numerical Modeling of the Viscoelastic Rayleigh-Benard Convection
Authors: Zheng Xin , Boutaous M’hamed , Xin Shihe , Siginer Dennis A. , Hagani Fouad , Knikker Ronnie
Published: January 2020

A new approach to the numerical simulation of incompressible viscoelastic Rayleigh-Bénard convection in a cavity is presented. Due to the fact that the governing equations are of elliptic-hyperbolic type, a quasi-linear treatment of the hyperbolic part of the equations is proposed to overcome the strong instabilities that can be induced and is handled explicitly in time. The elliptic part related to the mass conservation and the diffusion is treated implicitly in time. The time scheme used is semi-implicit and of second order. Second-order central differencing is used throughout except for the quasi-linear part treated by third order space scheme HOUC. Incompressibility is handled by a projection method. The numerical approach is validated first through comparison with a Newtonian benchmark of Rayleigh-Bénard convection and then by comparing the results related to the convection set-up in a 2 : 1 cavity filled with an Oldroyd-B fluid. A preliminary study is also conducted for a PTT fluid and shows that PTT fluid is slightly more unstable than Oldroyd-B fluid in the configuration of Rayleigh-Bénard convection.
Guidelines and Limitations of the Compact Compression Specimen
Authors: Plechaty David J. , Carpenter Kevin T. , Parmigiani John P.
Published: January 2020

Damage initiation and propagation material models for carbon fiber composites can be categorized according to the loading applied to constituent components. An example of such categorization is fiber tension, fiber compression, matrix tension, and matrix compression material models. Of these, matrix compression has been by far the least studied based on amount of published literature. Recent work at Oregon State University (OSU) has begun to address this lack of study. OSU researchers have published several papers culminating in the specification of an effective test specimen for isolating matrix compression damage initiation and propagation in carbon fiber laminates. While providing compelling results indicating the effectiveness and usefulness of this test specimen, little or no information has been provided regarding its manufacture, usable notch lengths, and optimum loading rate during testing. Experience at OSU has shown that this information is critical and not trivial to obtain. The purpose of this paper is to provide specific guidelines and “lessons learned” needed for other researchers to efficiently and effectively use this specimen in a comprehensive study. Test specimens are manufactured in the OSU Composites Materials Manufacturing Laboratory using typical commercial pre-peg carbon fiber following the specified layup and curing procedures. Once the material was cured the carbon fiber plate was then water-jet cut into the desired geometry and notch length. Usable notch length and optimum loading rate was determined by testing a series of specimens. All testing was conducted at an OSU lab using a universal testing machine with Digital Image Correlation (DIC) data collected. Specimens were preloaded and matrix compression initiation and propagation data collected until tensile failure occurred on the back edge of the specimen. Testing showed that shorter notch lengths result in inconsistent data and longer in effective initiation but limited propagation due to reduced ligament length. Testing suggested that a speed less than 5 mm/min gave the best results as faster displacement rates caused less crack propagation to occur, while increasing the likelihood of the specimen to fail in tension along its back edge. Through the use of these guidelines, researchers are able to manufacture and use an effective test specimen for the investigation of matrix compression damage initiation and propagation.
On Characterizing Uncertainty Sources in Laser Powder Bed Fusion Additive Manufacturing Models
Authors: Moges Tesfaye , Witherell Paul , Ameta Gaurav
Published: January 2020

Tremendous effort has been dedicated to computational models and simulations of Additive Manufacturing (AM) processes to better understand process complexities and better realize high-quality parts. However, understanding whether a model is an acceptable representation for a given scenario is a difficult proposition. With metals, the laser powder bed fusion (L-PBF) process involves complex physical phenomena such as powder packing, heat transfer, phase transformation, and fluid flow. Models based on these phenomena will possess different degrees of fidelity as they often rely on assumptions that may neglect or simplify process physics, resulting in uncertainty in their prediction accuracy. Predictive uncertainty and its characterization can vary greatly between models. This paper characterizes sources of L-PBF model uncertainty, including those due to modeling assumptions (model form uncertainty), numerical approximation (numerical uncertainty), and model input parameters (input parameter uncertainty) for low and high-fidelity models. The characterization of input uncertainty in terms of probability density function (PDF) and its propagation through L-PBF models, is discussed in detail. The systematic representation of such uncertainty sources is achieved by leveraging the Web Ontology Language (OWL) to capture relevant knowledge used for interoperability and reusability. The topology and mapping of the uncertainty sources establish fundamental requirements for measuring model fidelity and guiding the selection of a model suitable for its intended purpose.
DC-Biased AC Electrokinetics Effect on V-Shaped Electrode Patterns for Microfluidics Applications
Authors: Parvez Mohammad Salman , Rubby Mohammad Fazlay , Iqbal Samir , Islam Nazmul
Published: January 2020

AC electrokinetics is one of the widely used methods as an actuating mechanism in the lab-on-a-chip devices because of the absence of moving mechanical parts. In this paper, an analysis is done by using two perpendicular electrodes which are placed in V-shape to each other while maintaining an angle of 45 degrees with the third horizontal electrode. A semiconductive fluid was used to observe the microfluidic behavior and characteristics under the application of a DC biased AC signal. Applying the AC signal produced two different mechanisms of electrokinetics such as DC-biased AC electrothermal (ACET) and DC-biased AC electroosmosis (ACEO). In the ACEO process, a time-varying voltage was applied to the electrodes to create the double layer capacitance and zeta potential. This ACEO mechanism required lower voltage. On the other hand, the AC Electrothermal (ACET) flow produced a non-uniform electric field that generated spatially varying heat sources which in turn created a non-uniform temperature distribution. Two surface characteristics were also analyzed experimentally; one of these was by using the hydrophobic surface and the other used glass-surface only. At the microscale, mechanical microdevice encounter very high flow resistance and put stringent requirements on the strength of fluid channels, chambers and the interconnects. While many types of microfluidic manipulations can be effectively done by AC electrokinetics techniques, current research work focused on the observation of varying frequencies and voltages and their effects on microfluidic manipulations.
Nanoparticles Shape Effect on Thermal Conductivity of Nanofluids: A Molecular Dynamics Study
Authors: Hasan Roni Md. Rakibul , Morshed AKM M. , Tikadar Amitav , Paul Titan C. , Khan Jamil A.
Published: January 2020

Nanofluids have become the subject of theoretical and experimental researches over the few decades due to their enhanced heat transfer performance. In this study, thermal conductivity of copper argon nanofluids is determined through MD simulation. Different types of nanoparticles based on shape was used to make nanofluids. Role of different shape of nanoparticles such as cylindrical, cubical and spherical was disused. Green Kubo method is employed to determine the thermal conductivity of the nanofluids. Result shows that, for volume fraction 3% and 86 K system temperature, thermal conductivity enhancement of nanofluid containing spherical, cubical and cylindrical shape is 15%, 40% and 50% respectively compared with that of base fluid. Thermal conductivity enhancement of nanofluid for spherical particle at 86 K, 94 K and 102 K is 15%, 30% and 40% respectively while for volume fraction 3%, 6% and 9%, the enhancement is 15%, 35% and 45% respectively. The mechanism of increased heat transfer performance for different shape of the nanoparticles is discussed in this paper.
Design and Characterization of an Automated Assistive Knee Brace for Leg Muscle Rehabilitation
Authors: Zaidi Sohail , Huynh Austin , Thach Peara , Rubio Isaac , Patel Harsh , Viswanathan Vimal
Published: January 2020

The advances in the field of mechatronics and robotics have allowed us to create a variety of medical devices. Comparable advances are not reported in the area of rehabilitation and assistive devices. In the prior work, the authors have created an automated orthotic knee joint that provides assistance to the victims of partial paralysis. This device uses electromyography sensors to gather impulse signals and use pneumatic actuators in the form of fluidic muscles. A microcontroller is used to interpret the signals from the sensors and uses a feedback control loop to provide augmented strength and mobility to the wearer. This paper reports a couple of experiments performed to characterize the behavior of this knee brace. Firstly, the brace is operated stand-alone with the help of electromyography sensors attached to a healthy individual. The system provided reaction times from one to three seconds, which is reasonable for an assistive device. Next, the system is attached to a mannequin that mimics the behavior of a human knee. While the brace is observed to be behaving as expected, the reaction times were significantly higher than that of the natural motion of the human leg. The study provided insights about several parameters that need to be optimized before the brace is completely operational.
Relationship Between the Frictional Shear Stresses and the Normal Pressure on the Buttocks While Lying on a Spine Board
Authors: Pallerla Vinay Kumar , Hefzy Mohamed Samir
Published: January 2020

Cushions have been used on spine boards to reduce the interface pressure acting on the skin and thus prevent the formation of pressure ulcers. Several studies have focused on determining how using different types of cushions can reduce the normal interface pressure on the buttocks while lying on the spine boards. On the other hand, and while it has been agreed upon that the shear stresses contribute to the formation of pressure ulcers, this role has not been understood or quantified. The purpose of this work is to use 3-D finite element modeling to determine the contact frictional shear stresses at the buttocks while an individual is lying on a spine board when cushions of various stiffnesses are used.

The Zygote Solid 3D Male Human Anatomy model was used to construct a 3D CAD model of a section of the human body in the pelvic region. Skin, fat, muscles and bones were identified in the model. The Zygote SolidWorks model, the HyperMesh finite element preprocessor, and the ABAQUS software were used to create the finite element model. Bones were considered as an elastic isotropic material whereas skin, fat and muscles were modeled using Hyperelastic Neo-Hookean materials. Results were obtained to find the effects of body weight on the shear stresses while a person is lying flat with his buttocks contacting the spine board.

The results indicate that frictional skin shear stresses cannot be ignored since they were found to be, and depending on the cushion material, about 15% to 35% of the maximum normal pressure. We propose, and for the first time, a relationship to estimate the maximum shear stresses at the buttocks in terms of the maximum normal pressure for different Young’s moduli of cushions. These results can also be used as a guide to select cushion material that minimize normal and shear interface stresses.
Effect of Feedback Conditions on Blood Viscosity Estimation Method in Two-Dimensional Ultrasonic-Measurement-Integrated Blood Flow Analysis
Authors: Kishimoto Takuya , Kadowaki Hiroko , Tokunaga Takeshi , Mori Koji , Saito Takashi
Published: January 2020

Wall shear stress from blood flow is particularly considered to be a factor that promotes atherosclerosis, and is expressed as the product of blood viscosity and velocity gradient of blood flow. If in vivo wall shear stress can be evaluated by simultaneously measuring blood flow velocity and blood flow velocity gradient in real time, it is thought that blood viscosity estimation leads to elucidation of mechanism of arteriosclerosis and early detection.

In previous study, a blood viscosity estimation method was proposed by applying two-dimensional ultrasonic-measurement-integrated (2D-UMI) blood-flow analysis reproducing an intravascular blood flow field by feeding back an ultrasonic measurement to a numerical fluid analysis. The estimation accuracy was examined by a numerical experiment under specific conditions. However, the effects of analysis conditions on this method are not verified.

Accordingly, we investigated the effects of the feedback domain and the feedback gain on the estimation accuracy, and examined appropriate feedback conditions by a numerical experiment for a blood flow field of a straight blood vessel assuming a common carotid artery.

As a result, it was suggested that the estimation accuracy generally improves as the feedback gain is increased in a specific feedback domain.
Microfluidic-Based Fabrication and Dielectrophoretic Manipulation of Microcapsules
Authors: Maktabi Sepehr , Schertzer Jeffrey W. , Chiarot Paul R.
Published: January 2020

To probe the complexity of biological systems, large numbers of independent experiments are needed to gather statistically reliable information. A platform that performs these experiments at high-throughput demands precise control over the formation and delivery of microcapsules. Microfluidics enables passive and active modes of droplet formation, manipulation, and mixing. Aqueous- and organic-based emulsions serve as well-defined compartments that encapsulate target materials (e.g., cells, reagents, nucleic acid, and nanoparticles) in femto- to picoliter volumes surrounded by an immiscible fluid. In this work, we demonstrate a high-throughput PDMS-based microfluidic device for fabrication and control of uniform micron-size water-in-oil and oil-in-water emulsions. Passive and active modes of droplet generation (i.e., hydrodynamic flow focusing and electrospray, respectively) are utilized to form droplets in the size range of 1 to 100 μm. We also leverage dielectrophoretic forces to steer the microemulsions across flows of organic or inorganic phases. The dielectrophoretic force provides high-speed separation with no moving elements and does not require droplet charging. Two electrode designs of AC- and DC-based circuits incorporated into the PDMS block are proposed. We investigate the effect of frequency and voltage on the degree of deflection and separation efficiency of the emulsions. We show that the fabricated microcapsules can be used as templates to build synthetic lipid bilayer model membranes that more accurately mimic physiological conditions. In addition, our microfluidic-based device integrated with on-board electronics can be used as an essential component in high-speed screening bioassays.
Vibration of Beam-Type Resonant Biosensors With Time-Varying Mass Density
Authors: Hassanpour Pezhman
Published: January 2020

This paper investigates the dynamic response of a uniform beam with varying density. The governing equation of motion is derived using the Euler-Bernoulli model of the beam considering the dynamic effect of the change of the beam’s density. The dynamics of a beam-type resonant biosensor is investigated to demonstrate the effect of time-varying beam’s density. In this type of sensors, the density of the resonant beam changes with time due to the nature of absorption process. The absorption is modeled as an asymptotic exponential function of time. It is shown that the adsorption leads to a viscous damping force with a time-varying coefficient. The approximate solution of the governing equation of motion is derived for comparing with the exact solution. The response of the system is presented for several combinations of the system parameters. It is shown that two factors govern the viscous damping effect of the absorption process, namely the time constant of the process and the total change of the mass density over time. In general, a faster absorption process and greater change in mass density lead to more damping in the system. This is significant because a fast absorption rate and greater mass change are desirable design goals while damping is generally considered undesirable.
The Efficacy of Spreadsheet Modelling As an Alternative Means of Teaching Process Simulation
Authors: Armstrong Aaron , Kumpaty Subha
Published: January 2020

Spreadsheet based simulation has many advantages over the pre-programmed simulation applications more commonly used in teaching simulation in undergraduate courses. They are almost universally ubiquitous in business settings around the world. There is near certainty that students will have access to them after graduation since spreadsheets are a standard business tool used by nearly all engineers [1]. In addition, spreadsheets are already present within most standard operating systems. This means that there will be no need to buy or get approvals from Information Technology software committees or other managerial roadblocks. As an alternative to this, there are now free OpenOffice and LibreOffice spreadsheets available on most platforms which make their access effectively universal.

Aside from their excellent availability, spreadsheets are an extremely capable learning tool for best practices in process simulation. Most engineering students are arriving at college with a good set of spreadsheet skills from their primary education and then the rest tend to pick it up early as underclassmen [2]. Spreadsheet simulation is easy to explain and generally very simple to debug. Although the now mainly antiquated code-based simulation packages used to offer these same advantages, they have now been largely replaced by more graphically oriented packages which depend in part on subtle mouse clicks and sometimes complex sub-menu structures. In addition, spreadsheets offer easily accessible native analysis and excellent graphing capabilities.

Several advantages and potential disadvantages of spreadsheet simulation are presented in comparison to contemporary process simulation. Several simulation projects are then discussed related to Markovian processes including stochastic scatter patterns, sequential random object movement, multi-server queueing processes, dynamic intercept models, complex traffic and evacuation models, and Susceptible-Infected-Removed infections design simulations were taught using spreadsheet simulation.
Subject-Specific Models of the Head and Neck for Reproducing Experimentally Obtained Head Impacts in OpenSim
Authors: Mortensen Jonathan D. , Homayounpour Mohammad , Merryweather Andrew S.
Published: January 2020

Simulating impacts to the head that are likely to cause concussion contributes knowledge to inform efforts to reduce head injury risk in sports. Previous studies used generic models and potentially missed subject-specific factors, which when combined with experimental data may offer additional insights about an individual’s risk. This study details methods for creating more subject-specific OpenSim models of the head and neck, which can be used in future studies to evaluate head injury risk during impacts. A generic model was scaled to match subject height and weight using data available from the literature. Muscle strength and passive properties were also scaled in order to reproduce experimental data obtained during safe impacts to the head. The average error between experimental and simulation kinematic values was under 15% for all but one of the subject-models.

By applying the methods presented in this study, future work could include using subject-specific models to assess individual athletes and generate personalized training protocols to help prevent injury. Future work could also include subject-specific models to investigate the effects of posture, startle response, and auditory warnings on head injury metrics.
Enhanced Plasmonic Behavior of Metal Nanoparticles Surrounded With Dielectric Shell
Authors: Yuksel Anil , Cullinan Michael , Yu Edward T. , Murthy Jayathi
Published: January 2020

Metal nanoparticles have attracted intense attention due to their unique optical and thermal properties in various next generation applications such as micro-nano electronics and photonics. The near-field confinement between closely packed metal nanoparticles, which is enhanced due to their plasmonic behavior, creates high thermal energy densities under visible to near-infrared wavelength laser irradiation. As metal nanoparticles tend to be oxidized or change shape under laser illumination, resulting in nonlinear optical and thermal behavior, surrounding each metal nanoparticle with a dielectric shell could be a potential way to prevent these effects as well as to engineer their plasmonic behavior. In this study, we investigate energy transport within dimer and 4 nanoparticle (chain) configurations of 50 nm radius Au nanoparticles surrounded by dielectric shells under illumination from various laser sources in different dielectric media.
Inclined Injection of Under Expanded Supersonic Gas Jet
Authors: Sheridan A. M. , Srivastava S. , Henneke M. , Raza M. S. , Sallam K. A.
Published: January 2020

The injection of choked gaseous jets into the still air is investigated experimentally motivated by many industrial applications including flares and burners. The objective is to study the effect of injection angle on the jet mixing with ambient air. The experimental methods consist of particle image velocimetry (PIV) using pulsed Nd:YAG lasers of a choked gas jet, seeded with aluminum oxide particles, injected into still air, seeded with water fog. The computational methods consisted of 7.7 million cells simulation using Star CCM+. The test conditions include injection angles of 0°, 15°, and 30°. The results including mean and fluctuating velocities and the flow vorticity are presented. The flow field is not symmetric along the injection axis due to the asymmetric triggering of expansion fans at the jet exit due to the inclined injection plane. Moreover, the numerical simulation reveals the complex interaction mechanism of the expansion fans and shockwaves within the injection port.
Human-Powered Desalination Unit
Authors: Williamson A. J. , Sallam K. A.
Published: January 2020

The objective of this research is to design a human-powered desalination unit that can provide safe drinking water for a typical household in developing countries. The hypothesis of our study is that a human-powered machine operating on a Mechanical Vapor Compression (MVC) cycle can provide economically- and technologically-affordable drinking water without the use of expensive RO membranes. Thermodynamic analysis for human-powered MVC cycle with minimized pressure difference and small surface area is conducted. The design space included the following limitations: (i) only one compressor and only pump could be used, (ii) evaporation mass ratio was less than 0.7, and (iii) the water had to reach the minimum temperature required to inactivate bacteria, viruses, and protozoa. The effects of the concentration of salt in the waste brine were considered. The flow rate of clean water generated was calculated as a function of the required heat exchanger surface area; the primary cost factor in the design; as well as the compressor isentropic efficiency. The effect of the isentropic efficiency of the compressor on the unit performance was also investigated. The point of maximum efficiency in term of mass flow rate per unit surface area was calculated.
Effects of the Non-Newtonian Viscosity of Milk Flow in the Breast Ductal System
Authors: Azarnoosh Jamasp , Hassanipour Fatemeh
Published: January 2020

Numerical simulation of human milk flow inside the breast ductal system is carried out to investigate the impact of milk flow properties, specifically viscosity, on the flow regime. The geometry of the ductal system is assumed as a rigid body with six bifurcation levels. The vacuum pressure, obtained from clinical investigations, is applied as boundary conditions for numerical analysis. The simulations are performed by considering both Newtonian and Non-Newtonian milk flow properties. The streamlines of velocity fluid, wall shear stress, and milk flow expression for these two models are discussed. The results show that the non-Newtonian fluid has a higher magnitude of velocity compared to the Newtonian fluid, which leads to a greater amount of milk expression.
Modal and Harmonic Analysis of Girth Gear With Dual Mesh Pinions by Using Finite Element Method
Authors: Venkataraman Venkatesan , Keppanan Malar Mohan , Dhanasekaran Vinoth
Published: January 2020

In industrial ball mills, monitoring of girth gear and dual mesh pinion gearboxes are required for successful operation. In this paper, the dynamic response of an industrial ball mill is investigated through finite element analysis using ANSYS. A half symmetry model of the ball mill drive with anti-symmetry option is considered for the Finite element study to reduce the analysis time. Modal analysis is performed to extract the fundamental frequencies. A sufficient number of modes are extracted to capture at least 80 percent of total mass in each direction. Then, a harmonic analysis is performed by introducing a periodic exciting force on the ball mill. The dynamic response of the ball mill during resonance is studied.
Open Field Heating of Green Roofs and Small Arable Land Plots Using Waste Steam and Hot Water From Geothermal, Municipal and COGEN Sources to Enhance Plant Growth
Authors: Dell Robert , Petralia Michael Thomas , Pokharel Ashish , Unnthorsson Runar
Published: January 2020

The authors have been developing and testing an enhanced system of heated ground agriculture that uses buried plastic pipes to cool waste hot water and steam from municipal, CHP, and geothermal sources. The average heat dissipation rate is 3.3 kW of heat per square meter in test beds under 50 square meters. Plant data indicates increased yields of up to 20% and the successful small harvest of cultivars in outdoor settings that are only native to warmer climates. A heated green roof in New York City produced a small cotton harvest and January pansies. In 2018 a small harvest of non-indigenous oregano and turnips was commercially test marketed in Iceland. Test results indicate that a larger scale study to determine economic viability is warranted.
Mechanical Strength Degradation of Carbon Fiber Polymer Matrix Composites Exposed to Constant Low-Density Direct Current
Authors: Kotikalapudi Sai Tharun , Singh Raman P.
Published: January 2020

Carbon fiber reinforced composites (CFRP) can experience two dissimilar magnitudes of direct current during a lightning strike on an aircraft, a concentrated catastrophic high current followed by low direct current spread across the surface. Low density direct current can also occur in multifunctional composite structures for resistive heating, energy harvesting and storage. These direct currents lead to material degradation. Since CFRP structures are more susceptible to a lightning strike due to weak electrical and thermal conductivity compared to metallic bodies, considerable amount of research has been done to study the effects of instantaneous high current on mechanical properties. With the ever-growing demand for tailorable multifunctional composites, the effect of low direct current on mechanical properties of CFRP should be investigated. An experiment is designed to study the long-term exposure of low-density electric field effects on CFRP which are often coupled with detrimental thermal effects. In this study, experiments have been performed using an in-house setup to study the electrical effects of low constant direct current (DC) on cross-ply CFRP laminates. A constant current study has been conducted to characterize the voltage across the laminate over a period. The strength of the polymer depends on the integrity and type of bonds, the observed resistance change is a perceptible way of demonstrating the change in mechanical properties. The combined effect of electrical and thermal fields has been studied by mapping the surface temperatures continuously on the entire length of the laminate. Preliminary research showed that the presence of non-conducting epoxy undergoes localized dielectric breakdown near the carbon epoxy interface. In order to quantify the degradation, combined loading compression (CLC) and dynamic mechanical analysis (DMA) tests have been performed for coupon size samples which have been electrically degraded for a definite period. Compression test results are compared with electrical characterization and glass transition temperatures from DMA results.
Motion Estimation and Path Planning for Assistive Robotic Devices
Authors: Cheng Marvin H. , Huang Po-Lin , Chu Hao-Chuan , McKenzie E. A.
Published: January 2020

Assistive robotic devices have recently become a popular tool in various healthcare applications. To better assist users in their daily activities with robotic devices, adequate moving paths of joints need to be adopted based on user’s motions. In this paper, a motion predicting model was proposed. With the model developed using convolutional neural networks (CNNs), the corresponding type of motions can be determined efficiently in the initial state. A deriving procedure of common trajectories of desired motions has also been proposed using the approach of temporal alignment. These derived common trajectories are stored as a library. After the type of a specific motion being identified, paths are then synthesized to drive robotic devices with these derived common trajectories.
Total Blackout (Part 1)
Authors: Vogel Alois
Published: January 2020

Alois Vogel, Total Blackout
Cultural Studies als Fundierungsmöglichkeit von German Studies
Authors: Pekar Thomas
Published: January 2020

New Directions in German Studies
II. Situating Gender Studies in a Changing German Studies/Germanistik
Overview

Authors: Maria Veber Andrea Bandhauer and
Published: January 2020

New Directions in German Studies
III. Language Acquisition and the German Language Classroom
Overview

Authors: Boss Bettina
Published: January 2020

New Diiections in German Studies