bluuebunny/crossref_metadata_2025 huggingface dataset:
Implications of Non-Bingham Rheology
Authors: Pease Leonard F. , Bamberger Judith A. , Minette Michael J.
Published: January 2020

One of the key challenges now facing the US Department of Energy (DOE) is the fate of radioactive waste remaining from World War II and the Cold War, which is stored underground in tanks some 75 feet in diameter and over 30 feet tall. Over time, the waste has segmented into multiple layers with sludges and slurries at the bottom with salt crust layers often at the top and liquid in between. DOE’s current official baseline plans call for remaining sludges and slurries to be removed from the tanks and converted into a stable glass waste form. Minimizing worker exposure to radiation drives DOE to use slurry processing techniques to suspend, mobilize, transport, mix, and process the waste. Therefore, a clear and quantitative understanding of Hanford waste rheology is essential for the success of the DOE mission.

Historically much of the waste has been characterized using Eugene Bingham’s century old model that provides a straight line fit to higher shear rate data with the intercept suggesting a yield stress and the slope providing the consistency. Yet, Bingham fits overestimate the shear stress at a given shear rate for low to intermediate shear rates, exactly the range of shear rates typically encountered in pipe flow, where shear rates peak along the pipe wall and vanish in the center. This model produces a fictitious yield stress for some of the wastes that do not exhibit yield phenomena. While overestimating the yield stress may be prudent, safe, and conservative for some applications (e.g., pump sizing to ensure that pumps can handle yield stresses), overestimating the rheology may be inaccurate and non-conservative for other applications (e.g., eroding settled particle beds). Therefore, this paper evaluates the slurry rheology of Hanford and Savannah River wastes using a more modern rheological model that fits the full range of experimental data.

Although a bias has been recognized and alternative models proposed, the magnitude of this bias and the implications for tank waste have only been qualitatively suggested. The purpose of this paper is to evaluate quantitatively implications of the poor quality of fit between a Bingham model for rheology and experimental data at modest shear rates. We first demonstrate the magnitude of the bias between the data and the Bingham extrapolation. We then evaluate quantitatively the velocity profile under laminar conditions. This analysis shows that the bias may be large (hundreds of percent or more) at modest shear rates and that modest shear rates dominate pipe velocity profiles.
Heavy Truck Fuel Storage System Design for Improved Impact Protection
Authors: Leiss Peter J. , Mazza Marcus A. , Shipp Erin M.
Published: January 2020

Heavy (Class 8) truck fuel storage location and geometry has not significantly changed in several decades. Manufacturers have taken steps to improve their designs by eliminating cross over lines and making material property and thickness changes, among other changes, but there has been no mandate or significant effort to decrease the potential for post collision fuel fed fires in heavy trucks. Even with these design changes, FARS data indicates the number of fatal post-impact fires has not decreased over time. Several studies were conducted in the 1980’s and 1990’s that brought the unprotected design of the fuel storage on these vehicles to light. This paper combines these historical works with current FARS data on the subject and describes a different design approach that increases the impact protection of the fuel storage tank. This new approach uses the truck’s frame rails to guard the fuel storage tank and absorb and redirect impact energy. Currently, a heavy truck “saddle” mounted fuel tank’s integrity is tested through a 30 foot drop test prescribed by 49 CFR 393 and also listed in SAE Recommended Procedure J703. In this work, a crash test methodology used to test the integrity of a school bus side mounted fuel tank as prescribed in FMVSS 301S is discussed. Results of using this crash methodology on a current “saddle” tank design and a prototype of the new fuel storage system design are also presented.
Human Pelvis Bayesian Injury Probability Curves From Whole Body Lateral Impact
Authors: Yoganandan Narayan , DeVogel Nicholas , Pintar Frank , Banerjee Anjishnu
Published: January 2020

Injury criteria are used in military, automotive, and aviation environments to advance human safety. While Injury Risk Curves (IRCs) for the human pelvis are published under vertical loading, there is a paucity of analysis that describe IRCs under lateral impact. The objective of the present study is to derive IRCs under this mode. Published data were used from 60 whole-body Post Mortem Human Surrogate (PMHS) tests that used repeated testing protocols. In the first analysis, from single impact tests, all injury data points were considered as left censored and noninjury points were considered as right censored, while repeated testing results were treated as interval censored data. In the second analysis, injury data were treated uncensored. Peak force was used as the response variable. Age, total body mass, gender, and Body Mass Index (BMI) were used as covariates in different combinations. Bayesian survival analysis model was used to derive the IRCs. Plus-minus 95% credible intervals (CI) and their Normalized CI Sizes (NCIS) were obtained. This is the first study to develop IRCs in whole body PMHS tests to describe the human pelvic tolerance under lateral impact using Bayesian models.
Net-Zero Water (NZW) Reuse Desiccant Assisted Evaporative Cooling System for Data Centers
Authors: Okposio David , Nnanna A. G. Agwu , Abramowitz Harvey
Published: January 2020

The cooling effect of evaporative cooling systems is well documented in literature. Evaporative cooling however introduces humidity into the cooled space, which is unsuitable for data centers. Desiccants (liquid, solid or composites) adsorb moisture from the cooled air to control humidity and is regenerated using waste heat from the data center.

This work is an experimental and theoretical investigation of the use of desiccant assisted evaporative cooling for data center cooling according to ASHRAE thermal guideline TC 9.9 . The thickness of the cooling pads is varied with specific surface area, velocity of air through the pad measured, the product of the air velocity and surface area yields the volumetric flowrate of the air, the water flow rate varied as well. The configuration is such that the rotary desiccant wheel (impregnated with silica gel) comes after the evaporative cooler.

A novel water recovery system using the Peltier effect is proposed to recover moisture from the return air stream thereby optimizing the water consumption of evaporative cooling technology and providing suitable air quality for data center cooling.
Uncertainty Quantification of Wind Turbine Wakes Under Random Wind Conditions
Authors: Pereira Tássia Penha , Ekwaro-Osire Stephen , Dias João Paulo , Ward Nicholas J. , Cunha Americo
Published: January 2020

Understanding and minimizing the uncertainties in the wind energy field is of high importance to reduce the reliability risks and financial risks of wind farm projects. The present work aims to observe the levels of uncertainty in modeling the wake effect by attempting to perform statistical inference of a wake parameter, the wind speed deficit. For this purpose, an uncertainty propagation framework is presented. The framework starts by randomly sampling mean wind speed data from its probability density function (PDF), that is fed an inflow model (TurbSim), resulting in random full-flow fields that are integrated into an aeroelastic model (FAST), which results in the variability of the power and thrust coefficients of a wind turbine. Such coefficients and wind data, finally, fed the wake engineering model (FLORIS). The framework ends with the determination of the 95% coefficient intervals of the time-averaged wind speed deficit. The results obtained for the near and far wake regions introduce fundamentals in estimate the uncertainty in wind speed deficit of a single wind turbine wake and concludes that a systematic uncertainty quantification (UQ) framework for wind turbine wakes may be a useful tool to wind energy projects.
An Investigation of Temperature Measurement Granularity Towards Improving Li-Ion Battery Management System Design
Authors: Zandigohar Mehrdad , Lotfi Nima
Published: January 2020

Li-ion batteries have gained increased popularity in the past few decades as the main source in various mobile and stationary energy storage applications. Battery management system design, especially fault diagnosis, however, is still a challenge regarding Li-ion batteries. Traditional Li-ion BMSs rely on measurements from current, voltage, and temperature sensors sparsely located throughout the battery pack. Such a BMS is not capable of predicting battery behavior under various operating conditions; moreover, it cannot account for internal discrepancies among battery cells, incipient faults, the distributed nature of battery parameters and states, and the propagation effects inside a battery pack. Although majority of these effects have already been observed and reported, they are either studied in electrochemistry laboratories using in-situ techniques and detailed theoretical analysis or in practical manufacturing settings by engineers and technicians, which are typically considered proprietary information. The aim of this paper is to bridge the gap between these two domains. In other words, a detailed electrochemical/thermal simulation of a Li-ion battery cell under healthy and faulty conditions is performed to provide a better understanding of the exact spatial requirements for an efficient and reliable thermal management system for Li-ion batteries. The results of this study are specifically of great importance for battery fault detection and identification, mainly due to the recent advancements in distributed sensing technologies such as fiber optics.
Methane Emissions Reduction in Liquefied Natural Gas Off-Loading Process in Refueling Stations
Authors: Sharafian Amir , Blomerus Paul , Mérida Walter
Published: January 2020

Recent research into methane emissions from the liquefied natural gas (LNG) supply chain has revealed uncertainty in the overall greenhouse gas emissions reduction associated with the use of LNG in heavy-duty vehicles. Methane is the main component of natural gas and a potent greenhouse gas. This study investigates the impact of five methods used to offload LNG from a tanker truck to an LNG refueling station and estimate the amount of fugitive methane emissions. The LNG offloading process time, and the final pressures of the tanker truck and refueling station are considered to evaluate the performance of the LNG offloading methods. The modeling results show that the LNG transfer by using a pressure buildup unit has a limited operating range and can increase methane emissions by 10.4% of LNG offloaded from the tanker truck. The results indicate that the LNG transfer by using a pump and an auxiliary pressure buildup unit without vapor return provides the shortest fuel offloading time with the lowest risk of venting methane to the atmosphere.
Fugitive Methane Emissions: Development of a Mobile High-Volume Sampling System
Authors: Ramadhan Hadyan , Sharafian Amir , Mérida Walter
Published: January 2020

Liquefied natural gas (LNG) has been considered as a substitute for diesel and heavy-fuel oil in heavy-duty trucks and marine vessels, respectively. However, the widespread adoption of LNG as a fuel is hampered by its uncertain potential to reduce greenhouse gas (GHG) emissions in comparison with diesel and heavy-fuel oil from the lifecycle standpoint. Methane is the main component of LNG and a potent GHG. In this study, the design and validation of a high-volume sampling (HVS) system are proposed to accurately measure methane emissions from the LNG fuel infrastructure, including experiment designs for calibration and system validation, and uncertainty analysis. The accuracy of HVS measurements is tested under controlled environment. The results indicate that the HVS system can quantify leak rates between 108 and 3,254 g/h with a maximum uncertainty of 10% as long as the distance between the leak source and the HVS system sampling port is maintained at less than 50 mm. In future work, the HVS system will be used to characterize methane emissions from LNG offloading or bunkering process, and update the GHG inventories in North America to fill the knowledge gap in the complete lifecycle analysis of LNG fuel for heavy-duty vehicles and marine vessels.
Effects of Spraying Parameters on the Paint Transfer Efficiency in Air Spray
Authors: Zhang Simin , Wang Guolei , Liu Xingjie , Hua Xiaotong , Chen Zhiliang , Chen Ken
Published: January 2020

Automation is widely used for automotive paint application because of the repeatability of the resulting surface finish, as well as the benefit of removing humans from a hazardous environment. So the improvement of automobile coatings is significant. One compelling aspect of improvement is the paint transfer efficiency (TE), which is defined as the amount of paint that remains on a surface relative to the amount supplied to the paint applicator during coating operations. The effects of spray parameters namely shaping air pressure, atomizing air pressure, paint flow rate, spraying distance and spray velocity on paint transfer efficiency. A orthogonal experiment is designed to analysis the effects of spraying parameters on paint transfer efficiency. After the acquisition and analysis of all experiments, the relationship between spraying parameters and paint transfer efficiency is performed. Through variance analysis and regression analysis of experiment data, a conclusion following had been drawn: shaping air pressure has the strongest influence on TE, shaping air pressure and spray distance are inversely proportional to TE, atomizing air pressure is proportional to TE, paint flow rate and spray velocity nearly have no influence on TE.
Concurrent-Flow Flame Spread Over a Thin Solid in a Narrow Confined Space in Microgravity
Authors: Li Yanjun , Liao Ya-Ting T. , Ferkul Paul
Published: January 2020

A numerical study is pursued to investigate the aerodynamics and thermal interactions between a spreading flame and the surrounding walls as well as their effects on fire behaviors. This is done in support of upcoming microgravity experiments aboard the International Space Station. For the numerical study, a three-dimensional transient Computational Fluid Dynamics combustion model is used to simulate concurrent-flow flame spread over a thin solid sample in a narrow flow duct. The height of the flow duct is the main parameter. The numerical results predict a quenching height for the flow duct below which the flame fails to spread. For duct heights sufficiently larger than the quenching height, the flame reaches a steady spreading state before the sample is fully consumed. The flame spread rate and the pyrolysis length at steady state first increase and then decrease when the flow duct height decreases. The detailed gas and solid profiles show that flow confinement has competing effects on the flame spread process. On one hand, it accelerates flow during thermal expansion from combustion, intensifying the flame. On the other hand, increasing flow confinement reduces the oxygen supply to the flame and increases conductive heat loss to the walls, both of which weaken the flame. These competing effects result in the aforementioned non-monotonic trend of flame spread rate as duct height varies. This work relates to upcoming microgravity experiments, in which flat thin samples will be burned in a low-speed concurrent flow using a small flow duct aboard the International Space Station. Two baffles will be installed parallel to the fuel sample (one on each side of the sample) to create an effective reduction in the height of the flow duct. The concept and setup of the experiments are presented in this work.
Design and Fabrication of a Multi-Scale Fluidic Motherboard for a Universal Molecular Processing System (uMPS)
Authors: Park D. S. , Witek M. , Zhao X. , Kang Y. , Dathathreya K. , You B. H. , Soper S. A. , Murphy M. C.
Published: January 2020

A multi-scale fluidic motherboard, which can be used in a universal molecular processing system (uMPS) integrated with task-specific processing modules, was designed and fabricated in thermoplastics. The motherboard consists of a coverplate and a substrate. The coverplate included fluidic interconnects and thermal grooves on the top side, and the corresponding interconnects on the bottom side. The substrate was comprised of cell lysis microchannels, micromixers, and flow-connecting microchannels on the top side, and reservoirs for sample inputs and waste output, thermal grooves, and valve seats for flow control on the bottom side. The coverplates and substrates were fabricated with double-sided hot embossing of polycarbonate (PC) using four micromilled brass molds, two for the coverplate and another two for the substrate. Evaluation of the relative front-to-backside alignment for the double-sided hot embossing yielded an accuracy of 25 μm ± 14 μm (average ± standard deviation) for the coverplates and 30 μm ± 20 μm for the substrates. Thermal fusion bonding (TFB) of the coverplate and substrate was done using a spring plunger bonding setup with a range of temperatures and pressures. The motherboard bonded at 154 °C and 12.0 psi for 2 hours in a convection oven produced complete bonding with a little deformation of the valve seats. The complete motherboard will be integrated with the task-specific processing modules in the uMPS for investigating circulating markers from whole blood for precision molecular diagnosis of disease at low cost and with high fidelity.
Effect of Measuring Instrument Eccentricity and Tilt Error on Circularity Form Error
Authors: Ghosh Suhash , Sahay Chittaranjan , Malempati Poorna Pruthvi Chandra
Published: January 2020

From power stations to power tools, from the smallest watch to the largest car, all contain round components. In precision machining of cylindrical parts, the measurement and evaluation of roundness (also called circularity in ASME Geometric Dimensioning & Tolerancing Y14.5) and cylindricity are indispensable components to quantify form tolerance. Of all the methods of measuring these form errors, the most precise is the one with accurate spindle/turntable type measuring instrument. On the instrument, the component is rotated on a highly accurate spindle which provides an imaginary circular datum. The workpiece axis is aligned with the axis of the spindle by means of a centering and tilt adjustment leveling table. In this article, the authors have investigated the dependence of circularity form error on instrument’s centering error (also known as eccentricity) and tilt error. It would be intriguing to map this nonlinear relationship within its effective boundaries and to investigate the limits beyond which the measurement costs and time remain no more efficient. In this study, a test part with different circular and cylindrical features were studied with varying levels of predetermined instrument eccentricity and tilt errors. Additionally, this article explores the significance of incorporating these parameters into undergraduate and graduate engineering curricula, and be taught as an improved toolkit to the aspiring engineers, process engineers and quality control professionals.
Preliminary Results of Microwave Induced Thermoacoustics Imaging in Geological Media
Authors: Liu Chang , Mao Xu , Heredia Juesas Juan , Molaei Ali , Martinez-Lorenzo Jose Angel
Published: January 2020

Seismic and electromagnetic imaging modalities are conventionally used in subsurface situational awareness applications. These modalities have been very effective at characterizing the geological media in terms of its constitutive mechanical properties such as density and compressibility, as well as electromagnetic properties such as electric conductivity, permeability, and permittivity. In order to enhance these imaging capabilities, a Thermoacoustic (TA) imaging system is used in this work. TA imaging relies on the coupling of mechanical and electromagnetic waves through a thermodynamic process, and it has the potential to reconstruct thermodynamic constitutive properties such as volumetric expansion coefficient and heat capacity. TA imaging has been mostly used in biological applications; this is due to the low signal-to-noise ratio that can be created with this physical mechanism. This work is aimed at addressing such limitation and exploring the use of TA imaging in geophysical applications. Conventionally, a short microwave pulse excitation is used to create the TA wave; so that the stress confinement condition is met while providing high resolution images. This approach requires the use of expensive high power amplifiers to create a detectable TA signal. This limitation can be addressed by using a frequency-modulated continuous wave (FMCW) excitation, which has been recently proposed as a suitable mechanism to enhance the signal-to-noise ratio of the TA signal generated for a given peak power constrain. This paper discusses and compares both pulsed and FMCW TA imaging in geological media. Preliminary experimental results show the efficacy of this approach to image a rock immersed in an oil bath; thus paving the way towards its future use for subsurface sensing and imaging of fluid flow and transport in porous media.
Multidisciplinary Problem Based Learning: Venipuncture Practice Arm Research
Authors: Doan Phuong , Gomez Connie
Published: January 2020

Community colleges need more avenues for undergraduate research during their first two years in higher education but face challenges to building robust research namely the limited time frame students are at a community college and the limited resources for research. To maximize the limited resources and the educational experience for the students, multidisciplinary projects within the community college environment provide both engineering and science students with research opportunities that fit the schedule of a working student, allow interaction between disciplines, provide team-based environments, and foster life-long learning. This paper describes 1) a multidisciplinary project for honor chemistry and engineering students; introduction to engineering students and engineering graphics students in the development of a venipuncture practice arm for nursing students practicing venipuncture techniques in the simulation lab. 2) the institutional supports that promote the development of collaborative and multidisciplinary research projects and 3) recommendations for other community colleges interested in developing multidisciplinary research opportunities throughout their engineering and science curriculums.
Investigation of Sub Synchronous Vibration of Very High Speed Turbocharger Semi-Floating Bearing System: Prediction vs Test
Authors: R. Vengala Prasanth , Chandrasekaran Lokesh , Selvaraj Praveen Kumar , Arthanarisamy Subramani D.
Published: January 2020

Automotive engines are facing increased design focus towards downsizing, higher performance and lower emissions, in the process, challenging turbocharger (TC) technology to their limits. Downsizing of the engine needs smaller compressor and turbine wheels to achieve the critical flow requirements that leads to very high TC operating speeds of more 300k rpm. In general, TC rotor is most commonly supported by hydrodynamic fully floating (RFRB) or semi-floating bearing (SFRB) systems. For such high-speed applications, SFRB could be preferred bearing system where inner and outer bearing clearances act as a plain journal bearing and a squeeze film damper. These hydrodynamic bearings, exhibit non-linear oil whirl/whip phenomena in the inner bearing that leads to higher sub-synchronous vibration and overall deflection of the shaft. Sub-synchronous behavior of the SFRB is evaluated both numerically and experimentally (hot gas stand) for two design variants and results are published in this paper.

TCs were run up in hot gas stand and were recorded using NVH Data Acquisition System (DAQ) with frequency analyzers and eddy current displacement sensors. In numerical simulations, multi-body dynamics (MBD) of flexible rotor and housing structures are coupled with elasto-hydrodynamics (EHD) of the inner and outer oil films. The energy equation is considered for calculation of oil film temperature in EHD using thermal boundary condition obtained from 3D FE simulation. Detailed numerical investigation was conducted using EHD joint definitions in the above bearing system. Good agreement was obtained between test and prediction, and finer source characterization was achieved using simulation.
Wind Energy Harnessing System for Low and High Wind Speeds
Authors: Rashidi Majid , Kadambi Jaikrishnan R. , Ke Renjie
Published: January 2020

This work presents the design and analysis of a novel wind energy harnessing system that makes use of wind defecting structures to increase the ambient wind speed at geographic locations with relatively low wind speed. The system however reacts to highspeed wind conditions by altering the profile of the wind defecting structure in order to eliminate wind speed amplification attribute of the system, thereby protecting the wind turbine assembly at high speed wind conditions. Although increasing the wind speed is advantageous at geographic locations that the wind speed is typically low; however, from times to time, there could be sustained high-speed wind conditions at the same locations that may damage the wind turbine systems that take advantage of the wind defecting structures. The present work disclosed a wind deflecting structure formed by at least two sail-like partial cylindrical structures that are supported atop of a tower-like foundation in a symmetric arrangement, where one or more wind turbines can be installed in the space between the two partial cylinders. The two partial cylinders, each substantially in form a quarter cylinder is made of plurality of parallel ribbed-like bars, hereafter referred to as “bars” with a flexible thin material that are mechanically supported by the bars. The bars are oriented in a direction perpendicular to the ground; allowing the wing deflecting structures to accept horizonal axis or vertical axis turbines in the space between them. The function of the bars is to allow the thin material, attached to them, to assume a curved configuration substantially in the form of a quarter cylinder. The apparatus is equipped with wind speed monitoring devices, and power source and power transmission means, such as cable-pulleys, chain-sprockets, gears, or mechanical linkages that all work in concert to deploy or stow the thin material along the vertical rods depending to the magnitude of the prevailing wind speed. Preliminary computational fluid dynamics analyses have shown that the wind deflecting structure proposed here in amplifies the wind speed by a factor of 1.65.
Experimental Investigation of PolyJet 3D Printing Process: Effects of Orientation and Layer Thickness on Thermal Glass Transition Temperature
Authors: Sanders Jackson , Wei Xingjian , Pei Zhijian
Published: January 2020

The J750 PolyJet printer is the newest model of full-color and multi-material 3D printer from Stratasys. Currently, limited information is available about the effects of control factors on thermal glass transition temperature of parts printed by this printer. In this study, the effects of two control factors, printing orientation and layer thickness, on the thermal glass transition temperature (Tg) are investigated. The results suggest that both control factors significantly affect Tg. Specifically, samples printed using the high mix mode have higher elastic moduli than those printed using high quality mode. Larger values of elastic moduli directly lead to a higher thermal glass transition temperature, making the material more effective under relatively extreme temperatures and duress. These results would be valuable to researchers and practitioners who use the Polyjet 3D printer.
Osteoporotic Bone Augmentation Utilizing Curved Pattern of PMMA Injection: A Combined Finite Element and Optimization Investigation
Authors: Farvardin Amirhossein , Armand Mehran
Published: January 2020

A potential effective treatment for prevention of osteoporotic hip fractures is augmentation of the mechanical properties of the femur by injecting it with Polymethyl-Methacrylate (PMMA). We have previously developed a preoperative planning workstation to optimize the pattern of cement injection. In this planning paradigm, injections occur on a straight line limiting the overall match between the optimal and injected volumes of the cement. In addition, new advancements in drilling techniques has made it possible to plan and drill the bone based on a curved trajectory. In this study, we introduced a methodology to find the optimal drill path for PMMA injection. With the aid of Finite Element (FE) and hydrodynamic simulations, the effectiveness of the proposed approach was evaluated. Results showed that with an average injection of 7.2 ml, the proposed method can increase the yield load of the femur by 69%. Future works involve experimental validation of this method in cadaveric studies.
Residential Heating System Control for Future Electric Power Grid Services Using Minimal Measurements
Authors: Brambley Michael R. , Lian Jianming
Published: January 2020

The study presented focuses on control of central electric resistance heating (often referred to as electric furnaces) in a manner to meet a specified target reduction in average electric power demand over 5-minute utility verification periods. The paper describes a supervisory control method that uses a small number of sensed points to meet these target power demand reductions while ensuring that indoor temperature is maintained within a comfortable range. Testing of the control method is performed in two identical test homes with the control methodology augmented to account for practical complexities in the operation of the heating system equipment (e.g., minimum-off [lock-out] time, response activation delay, and data latency). The test homes, equipment in them, data collection apparatus, and control platform are described as well as results of the testing.

The analysis of results shows the potential for control of electric heating systems to provide demand response as well as some limitations when used alone without coordinated control with other end-use equipment and appliances. Discussion of results includes a brief introduction to a method for coordinated control of multiple appliances in homes and identification of potential future research to realize the underlying vision of homes providing services to the power grid.
A Computational Fluid Dynamics (CFD) Study of Pneumatic Atomization in Aerosol Jet Printing (AJP) Process
Authors: Salary Roozbeh (Ross) , Lombardi Jack P. , Weerawarne Darshana L. , Rao Prahalad K. , Poliks Mark D.
Published: January 2020

Aerosol jet printing (AJP) is a direct-write additive manufacturing method, which has been utilized particularly for the fabrication of flexible and hybrid electronics (FHE). In spite of the advantages of AJP — e.g., high-resolution material deposition on nonplanar surfaces and accommodation of a wide renege of ink viscosity — AJP inherently is a complex process, prone to nonlinear process changes. Consequently, real-time process monitoring and control (with an understanding of the physics behind aerosol generation and transport) are inevitable. The overarching goal of this work is to establish a physics-based framework for process monitoring and closed-loop control (for correction) in AJP. In pursuit of this goal, the objective is to forward a CFD model to explain the underlying physical phenomena behind aerosol nebulization in AJP. To realize this objective, a 3D compressible, turbulent multi-phase flow CFD model is forwarded. The geometry of the pneumatic atomizer is modeled based on X-ray computed tomography (CT) imaging. The boundary conditions of the problem are defined based on experimental observations. The outcome of this study paves the way for understanding the complex mechanisms of aerosol generation in AJP and also design of efficient atomizers.
Improving the Performance of Centrifugal Pumps in Serial and Parallel Configurations Using Digital Twins
Authors: Carrillo Peña Andrés L. , Eugenio Barroso Jeffer S. , Martínez Vesga Alberto A. , Roa Prada Sebastián , Ardila Acuña Victor A.
Published: January 2020

Centrifugal pumps are devices commonly used in countless industrial and residential applications, from water supply systems to oil and gas processing plants. These rotatory hydraulic machines have a strong impact on the energy consumption of industry worldwide, not only because of their vast amount but also because of their continuous operation. Therefore, developing techniques to improve the efficiency of pumping systems is of great help to make communities and industrial activity more sustainable. The overall performance of these pieces of machinery cannot be fully predicted by means of analytical procedures due to the complexity of the fluid flow phenomena that occurs in their interior, so it is common practice to resort to alternate modeling techniques, such as computer aided numerical analysis, which can predict the performance of a pump, given its CAD computer model. However, the performance of an actual centrifugal pump may deviate from its ideal behavior due to multiple causing factors which may alter the performance curves given by the manufacturers in the corresponding data sheets. The discrepancies between the real and the simulated responses of centrifugal pumps demand for better modeling and simulation techniques to improve the design of more efficient pumping systems. Digital twins have the ability to bring the simulation environment closer to reality, by replicating the behavior of the physical system in a simulation environment with the support of experimental data. The digital twin of a multiple pumps system with serial and parallel configurations was developed, based on two identical industrial centrifugal pumps available in the laboratory. Experimental data was collected to calibrate the digital twin system so that the simulated system can predict the response under changing operating conditions. The simulation environment was developed with the assistance of a commercial Computational Fluid Dynamics computer program. After validating the behavior of the virtual components, with respect to the behavior of their actual counterparts, tests were carried out to predict the behavior of the pumping system in case of downstream disturbances which can affect the operating point of the overall pumping system and its corresponding efficiency. The development of the digital twin for the pumping system allowed visualizing how the pumps connected in series or in parallel can be maneuvered to adjust its operating conditions to achieve higher efficiency operating conditions in response to changes in the conditions downstream in the pipeline.
Wheel Slip Regulation for Heavy Commercial Road Vehicles Using Model Predictive Control Subsumed With Auto-Regressive Time-Series Modelling
Authors: Gaurkar Pavel Vijay , Challa Akhil , Subramanian Shankar C. , Vivekanandan Gunasekaran , Sivaram Sriram
Published: January 2020

Wheel Slip Regulation (WSR) is one of the Active Vehicle Safety Systems (AVSSs) for maintaining vehicle stability and maneuverability during emergency braking An approach for wheel slip prediction is proposed in this paper, which involves Auto-Regressive (AR) Time-Series modelling of longitudinal vehicle acceleration. This technique allows the usage of linear longitudinal vehicle dynamics for wheel slip estimation. A wheel slip prediction model was developed considering measurements from accelerometer and wheel speed sensor. This modified the Model Predictive Control (MPC) formulation to a univariate control input problem, involving braking torque. The objective function was devised for solving a least-squares reference tracking problem. An analytical solution for the MPC optimization problem was derived and implemented towards WSR. The proposed framework was programmed in MATLAB Simulink® and co-simulated with IPG TruckMaker® (a vehicle dynamic simulation software). The algorithm was tested in a Hardware-in-Loop (HiL) setup consisting of a pneumatic air brake system interfaced with IPG TruckMaker®. Open loop studies from HiL led to the inclusion of Kalman filter for estimate tuning and PID inner loop control for brake pressure transients, which improved wheel slip regulation.
Verification and Validation of Droplet Freezing for Convective Boundary Condition Using Matched Asymptotic Perturbation Method and Computational Fluid Dynamics
Authors: Akhtar Saad , Xu Minghan , Sasmito Agus
Published: January 2020

Droplet freezing has been a subject of several studies encompassing numerous applications such as food processing, spray freeze drying, ice accretion on the aircrafts and low temperature biological applications. The literature is rife with a comprehensive analytical and numerical treatment of the classical Stefan problem. There is a need, however, to address the development of accurate solutions for the two-phase Stefan problem where the initial droplet temperature is different than the freezing temperature of the droplet. A solution of such kind will allow for quick and convenient calculations for important geometric and operating parameters over a wide range.

This study presents a computational fluid dynamics model along with a perturbation series solution approximation developed for the temperature field and the interface motion. The semi-analytical results are compared with experimental results in the literature and are further complemented by a computational fluid dynamics study of a freezing droplet using enthalpy-porosity method. Preliminary results indicate a good agreement between experimental, numerical and perturbation series solutions.
Heat Transfer Characteristics of Various Gun Barrels Under Different Operating Conditions
Authors: Gadalla Mohamed , Jasim Muhammad , Ahmad Omar
Published: January 2020

The thermal stability parameter is an important parameter for predicting the lifespan of structures. In this paper, a two-dimensional transient heat transfer model of machine gun barrels undergoing continuous firing developed and analyzed for different geometries and thermal properties. The model for the transient thermal analysis is based on the forced convection heat transfer at the inner surface of the gun barrel. Finite element simulations were performed to predict the interior and exterior barrel temperature profiles and temperature contours after continuous firing process. The incomplete Cholesky Conjugate Gradient (ICCG) solver was adopted in solving unsymmetrical thermal transient analyses. The material thermal behavior studied for the basic circular cross section of gun barrels showed that the lowest inner wall temperature was for high rounds was achieved in steel barrels due to the rapid conducted and convective heat transfer to the environment. While the highest inner wall temperature was recorded for ceramic STK4 barrels and an increase of inner wall temperature by 17% was observed as compared to the typical case of circular cross section steel barrel. In general, a higher inner temperature in the gun barrel is undesirable and harm due to the possibility of reaching the cook-off scenario at earlier rounds. Results concluded that non-circular geometries with constrained cross section areas of typical case improve thermal management and the hexagonal geometry had the best thermal management and could provide more rounds for users. In addition, titanium barrels would have a weight drop of 41% while the overall barrel’s temperature increases by 49%.
Mechanical Design and Development of a Payload for Structural Health Monitoring Experiments on the International Space Station
Authors: MacNinch Douglas , Pacheco Daniel , Tandon Arjun , Bancroft Carl , Flores Isaac , Rue Matthew , Zagrai Andrei
Published: January 2020

This contribution reports design and development of a payload for structural health monitoring (SHM) experiments on the International Space Station (ISS). The payload was designed to operate in low earth orbit (LEO) environment and fit specifications of the Materials International Space Station Experiment (MISSE) module. In particular, LEO environmental factors such as a strong vacuum, thermal variations from −18°C to 60°C [1], and background radiation were considered. The payload is a rectangular multi-leveled structure which houses several SHM experiments, active sensors self-assessment, and electronic hardware with data storage and retrieval capabilities. SHM experiments include guided wave propagation in a metallic structure, monitoring of an imitated crack, assessment of a bolted joint, investigation of structural vibration via electromechanical impedance method, and acoustic emission monitoring. In addition, piezoelectric sensor self-assessment is realised using impedance diagnostics. It is anticipated that the payload will operate for one year in LEO and provide insights on the effect of space environment on SHM of future space vehicles during long-duration flights. This contribution focuses on mechanical design of the payload to support SHM experiment. Specific arrangement of payload elements and implementation of boundary conditions for SHM experiments are reported. Theoretical calculations and examples of SHM experimental data obtained in laboratory tests are presented and discussed in light of expected variations due to LEO environment. Measures to protect SHM hardware from harsh space environment are presented. Perspective applications of SHM as an integral component of future space systems are discussed.
A Finite Element Simulation Study on the Properties of a Multi-Material Based Auxetic Metamaterial
Authors: Su Yutai , Wu Xin , Shi Jing , Wang Jin
Published: January 2020

Auxetic metamaterials have unique structural designs exhibiting zero or negative Poisson’ ratios during stretch/compression processes, which enable many critical applications such as sensing technology, wearable devices, and weight reduction parts. However, it is difficult to achieve ideal performance of various structural designs through geometry manipulation due to the beam/wall buckling under large strain. One way to minimize the occurrence of buckling is by introducing the high elasticity on the joints, but trade-offs exist among different mechanical behaviors. To this end, this study proposes to use a multi-material combining with the structure optimization to design an auxetic structure. The basic re-entrant structure is employed due to its simplicity, and finite element method (FEM) is adopted to demonstrate the effectiveness of this newly proposed strategy regarding the auxetic behaviors. For this multi-material structure, a different Young’s modulus is designed to apply on the additional arch structure. A series of simulations, which consider the influence of the mechanical properties, are conducted to investigate the change of auxetic behaviors such as stress distribution, Poisson’s ratio, and equivalent Young’s modulus against the applied material properties. The results indicate that the mechanical properties are strongly affected by the geometry design and the applied materials properties. Meanwhile, the buckling effect of the beam/wall could be eliminated if the hinge strength is small enough. The trade-off between equivalent mechanical properties and Poisson’s ratio could also be tuned through this newly material-based design.
Effects of Extrusion Temperature and Printing Direction in Bioprinting on Profile Accuracy of 3D Printed Constructs
Authors: Thakare Ketan , Wei Xingjian , Qin Hongmin , Pei Zhijian
Published: January 2020

In extrusion-based bioprinting, 3D printing process parameters affect dimensional accuracy of printed constructs. However, little information is currently available on effects of extrusion temperature and printing direction on dimensional accuracy of 3D printed constructs using Alginate:Methylcelluolose hydrogel. In this study, strand thickness of 3D printed constructs printed at temperature of 35°C, 40°C, 45°C and at vertical and horizontal printing direction were measured. The statistical analysis revealed that extrusion temperature and printing direction have significant effect on the strand thickness of 3D printed constructs.
A New Incremental Harmonic Balance Method With Two Time Scales for Quasi-Periodic Motions of an Axially Moving Beam With Internal Resonance Under Single-Tone External Excitation
Authors: Huang Jianliang , Zhu Weidong
Published: January 2020

In this work, a new incremental harmonic balance (IHB) method with two time scales, where one is a fundamental frequency, and the other is an interval distance of two adjacent frequencies, is proposed for quasi-periodic motions of an axially moving beam with three-to-one internal resonance under singletone external excitation. It is found that the interval frequency of every two adjacent frequencies, located around the fundamental frequency or one of its integer multiples, is fixed due to nonlinear coupling among resonant vibration modes. Consequently, only two time scales are used in the IHB method to obtain all incommensurable frequencies of quasi-periodic motions of the axially moving beam. The present IHB method can accurately trace from periodic responses of the beam to its quasi-periodic motions. For periodic responses of the axially moving beam, the single fundamental frequency is used in the IHB method to obtain solutions. For quasi-periodic motions of the beam, the present IHB method with two time scales is used, along with an amplitude increment approach that includes a large number of harmonics, to determine all the frequency components. All the frequency components and their corresponding amplitudes, obtained from the present IHB method, are in excellent agreement with those from numerical integration using the fourth-order Runge-Kutta method.
Development of Vehicle Safety Rating Systems and Application to Off-Road Vehicles
Authors: Kebschull Scott A. , Van Auken R. Michael
Published: January 2020

The first vehicle safety rating systems were the US National Highway Traffic Safety Administration’s New Car Assessment Program (NCAP), started in 1979, and the Australasian NCAP, started in 1992. These systems were investigated in order to determine the methods used to develop them and the characteristics that make them scientifically valid. In addition, a proposed safety rating system for All-Terrain Vehicles (ATVs) and Side by Side Vehicles (SSVs) was compared to the automotive NCAP systems in order to determine its scientific validity. The literature related to the history and development of the original NCAP safety rating systems was reviewed. The proposed safety rating system for ATVs was also reviewed and comparisons with the original NCAP systems were made. The original NCAP systems have been based on correlations between the measured acceleration of the head and chest and actual injury outcome probabilities. These systems also were intentionally restricted to providing comparisons between vehicles of similar mass. Based on this premise, criteria for the establishment of a vehicle safety rating system have been developed with the aim to ensure that such a system has validity and provides ratings that are based on scientifically established correlations between objectively and repeatably measured values and desirable safety outcomes. The proposed safety rating system for ATVs and SSVs that was not developed following this method was found to have no basis in known relationships between the test outcomes and injury probabilities. Although the proposed safety rating system for ATVs and SSVs was found to be unacceptable, a methodology for developing a safety rating system that would meet the criteria is proposed. The methodology would involve collecting real-world injury and exposure data and correlations with measurable vehicle characteristics. This correlation could then lead to the development of scientifically valid safety rating systems for ATVs and SSVs.