bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Ice Propagation and Salt Diffusion in Freezing Desalination
Authors: Zhang Hongtao , Janajreh Isam 
Published: January 2022

Abstract
Freezing desalination (FD) is attractive and more sustainable option due to the low energy consumption and less maintenance. However, technical challenges such as low freezing rate and process complexity arising from the salt trapping in the produced ice hinder the commercialization of this method. In this work, freezing experiments of water-NaCl solution are carried out to investigate the ice propagation and its salinity distribution to understand the salt trapping phenomena. Results reveals subcooling followed by a homogenous temperature jump occurs in the solution at an early stage of freezing suggesting ice freezing happens to large solution bulk. The Ice-front in brine is also characterized with many sharp and disorderly ice tips and there are many channels filled with liquids inside the formed ice block. This heterogeneous growth of ice promotes salt trapping. The salt distribution in the formed ice reveals that the salinity gradient in that early freezing stage is quite small and it rises dramatically at the last several layers of ice. The salinity in the first 10% frozen ice is only half of initial salinity which suggests a suitable freezing fraction of initial solution in freezing desalination. Finally, the developed first principle model based on the obtained salinity gradient is proved to be reasonably accurate to predict the freezing time with acceptable discrepancies and less computation cost.
Increased Vehicle Intrusion as a Result of Vehicle Weight
Authors: Eichaker Lauren , Trepeck Cameron , Arnett Michael , Chen H. Fred , Wiechel John , Guenther Dennis 
Published: January 2022

Abstract
Vehicle accidents remain a leading contribution to accidental deaths in the United States. Recently, there has been increased interest on how differences in cargo loading affect crash kinematics. This paper demonstrates that at a particular speed, increases in the vehicle cargo weight can influence the magnitude of the vehicle deformation. Larger deformations may involve greater intrusion into the occupant space. This increased intrusion may adversely affect the injury potential for the occupant by reducing survivable space and overcoming safety features. Additionally, an accident reconstructionist may need to consider the difference in cargo loading and distribution when calculating specific accident characteristics in their analyses. For example, the kinetic energy change between loaded and unloaded conditions is a feature of interest during vehicle collisions. These concepts were validated using Engineering Dynamic Company’s (EDC) Human, Vehicle, Environment (HVE) accident reconstruction software. The HVE analysis included simulating impacts of vehicles with varying cargo loads; HVE was also used to visualize the concepts described above. The case studies will have approximately similar BEV’s, crash speeds and other vehicle characteristics.
Verification Study of the Nuclear PRA for the Mars 2020 Mission Following Accidental Orbital Re-Entry
Authors: Earthperson Arjun , Diaconeasa Mihai A. 
Published: January 2022

Abstract
Today, Probabilistic Risk Assessment (PRA) plays a vital role in assuring mission success for robotic and crewed missions alike. Current-day PRA techniques integrate multimodal, often black-box analyses to build comprehensive risk profiles. This paper describes a review and verification study of the “Nuclear Risk Assessment for the Mars 2020 Mission Environmental Impact Statement” (N-PRA)[1]. Sandia National Labs conducted the N-PRA for NASA’s Jet Propulsion Laboratory (JPL). More specifically, we have verified the source term calculations associated with the release of radionuclides from a Multi-Mission Radiothermoelectic Generator (MMRTG) power source for a limited set of accident scenarios in the case of an accidental re-entry into Earth Orbit with an Earth impacting trajectory.
We achieve this by using analytical methods[2] historically implemented for the Cassini Mission PRA[3] for a failed planetary swingby gravity-assist. Our results are within 28% to 56% of the referenced study. Limitations in our methodology are attributed to a lack of modern simulation-based tools and deterministic methods for modeling complex physical phenomena. The results are interpreted and compared with the values presented by the initial authors, along with comments for improving our current methodology.
Temperature-Dependent Impact Properties of ABS Polymer
Authors: Kratzok Max , Saigal Anil , Zimmerman Michael 
Published: January 2022

Abstract
Polymeric materials are composed of chains of molecules known as monomers which are held together by secondary bonds. Amorphous polymers have a glass transition temperature above which their behavior transitions from glassy to viscoelastic, meaning they act like both a viscous liquid and an elastic solid. This concept may seem familiar to anyone who has used Silly Putty®; bouncing a ball of Silly Putty causes the material to behave elastically whereas it will flow into a puddle if left on a table overnight.
Time temperature superposition (TTS) describes the dependence of viscoelastic mechanical properties on time and temperature. Repeating the Silly Putty experiment at a different temperature will change how long it takes to reach the same end mechanical property. The Williams-Landel-Ferry (WLF) equation empirically defines the relationship between a temperature shift and a shift in the timescale for a specific material property. It has been widely used for materials undergoing low rates of strain (e.g. creep, stress relaxation), but it applies to any property of viscoelastic behavior.
This paper examines modeling the temperature-dependent impact behavior of polymers based on the WLF equation. Although polymers experience viscoelastic behavior for an incredibly short time prior to fracture, the strong temperature dependence and past literature suggest the validity of the WLF equation to higher rates of strain as demonstrated herein for the energy absorption of acrylonitrile-butadiene-styrene (ABS) undergoing high-velocity multiaxial impact tests.
Numerical Study of Deformation of Viscoelastic Drop Migrating Through Microchannel With Sudden Constriction
Authors: Prasad Niraj Kr , Sankar Ghosh Siddhartha , Dalal Amaresh 
Published: January 2022

Abstract
In this paper, deformation of viscoelastic drop in a microscale flow with sudden constriction is studied numerically. . The effect of polymeric viscosity on deformation of viscoelastic fluid is studied for two different solvent viscosity ratio and two different channel confinement in two-phase viscoelastic drop-Newtonian matrix system. The Finitely Extensible Non-linear Elastic–Peterlin (FENE-P) model was used to model the viscoelastic drop. The simulation was performed using open source solver Basilisk. The viscoelastic drop with lower polymeric viscosity and higher solvent viscosity seemed to undergo appreciable deformation inside constricted microchannel when subjected to sudden contraction. The low polymeric viscosity of a viscoelastic fluid corresponds to a dilute polymeric solution, its viscoelastic behavior is best explained by seeing its deformation under high shear flows inside microchannel. The isolated arrangement of polymeric coils in dilute polymeric solutions assists independent molecular movement, which supports their deformation under high shear flows. The FENE-P drop model used in the present study, at higher solvent viscosity, exhibit faster stress relaxation and remarkable elastic recovery in the expansion zone of the microchannel. The dilute FENE-P viscoelastic fluid can also be considered as a significant model to predict the viscoelastic behavior of useful polymeric fluids like hydrogels, paints, and vesicles, etc.
Evaluation of “Natural Gas/Hydrogen” Mixtures for Power to Gas Application
Authors: Incer-Valverde Jimena , Olaniyi Oyeniyi , Morosuk Tatiana , Tsatsaronis George 
Published: January 2022

Abstract
Utilization of hydrogen (H2)/natural gas (NG) mixtures or pure hydrogen in gas-fired power plants poses a lower carbon footprint instead of the regular 100% NG fuel. Reducing carbon emissions (CO2) in electricity production is fast gaining huge traction in gas power plants, as the attention is shifting from soon eradicated coal power plants to low carbon power plants. Increased interest in the hydrogen economy has further aroused discussions for hydrogen to replace natural gas. This paper evaluates the impact of hydrogen mixtures on existing power plants in three countries: Denmark, Germany, and the United Kingdom. The investigation is carried out using energy, exergy, and economic analysis to depict implications of the various mixtures on each of the power plants. The simulation of the power plants was performed using Ebsilon software, while the calculations of CO2, and NOx emissions were carried out with the aid of the Cantera software and the exergy-based analysis was computed in Excel VBA. The analyzed mixtures of H2/NG presented advantages in all the power plants studied such as lower CO2 emissions, higher energetic and exergetic efficiencies, and, therefore, lower mass flowrates of the fuel mixture. However, NOx discharge, levelized fuel cost (except in the Viborg power plant), and volumetric flowrate increased drastically. Conclusions of this paper will enlighten readers on the technological and economic constraints of using H2-NG mixtures in gas-fired power plants.
Mixed-Integer Nonlinear Programming (MINLP) Based Optimization of Refrigeration Systems
Authors: Mussati Sergio F. , Morosuk Tatiana , Mussati Miguel C. 
Published: January 2022

Abstract
This paper addresses the optimization of refrigeration systems by proposing a deterministic model involving both discrete and continuous decisions. The superstructure-based representation of vapor compression-absorption cascade refrigeration system, recently presented by the authors, is properly extended to include more candidate configurations as well as a cost model considering capital and operation expenditures. The proposed superstructure representation is then formulated as a mixed-integer nonlinear programming (MINLP) model and solved using an optimization algorithm based on the generalized reduced gradient method. The mass flowrate, pressure, temperature, composition of all streams, and the energy transferred with the associated heat transfer area and driving force of all process units are simultaneously optimized. The optimal configuration is selected from the proposed superstructure. The resulting optimization model is inherently combinatorial in nature and involves more than 20 candidate combinations. A study case is presented in order to show the utility of the proposed model. Given the desired design specifications — refrigeration temperature and capacity — the model allows obtaining the optimal configuration, process-unit sizes, and operating conditions that minimize the total annual cost. As a result of the model, the optimal configuration consisting of a stand-alone compression cycle with R717 is selected from the proposed superstructure to achieve 100 kW at −20 °C. Then, this optimal solution is compared with a solution obtained with a fixed configuration consisting of a vapor compression-absorption cascade refrigeration system which is a sub-optimal solution compared to the stand-alone compression cycle.
Mechanical-Electrical Behavior of Multifunctional Energy Storage Composites
Authors: Bombik Anthony , Ha Sung Yeon Sara , Nasrollahi Amir , Haider Mohammad Faisal , Chang Fu-Kuo 
Published: January 2022

Abstract
Multi-functional Energy Storage Composites (MESC) are composite sandwich structures where battery stack layers are placed between two layers of CFRP and sealed by low-density polyethylene (LDPE), forming a unified material. Because the layered Li-ion stacks have negligible out-of-plain shear stiffness, the two CFRP sheets on both sides of the battery are connected using LDPE rivets that pass through holes cut through the battery layers. The shear transfer mechanism of the rivets substantially enhances the shear stiffness and strength of the MESC. As the first step of preparing a guide for MESC design, the highly coupled mechanical and electrical behavior of MESC was studied through experiments. Several MESC cells were tested under three-point-bending loads. The load, deformation, and electric potential of the MESC were measured, and the electrical and mechanical failures were observed. A finite element model was developed to simulate the electro-chemo-mechanical coupling effect in MESC. In this model, a new constitutive relation of the battery material is proposed and verified by the experimental results. The resulting model can be used to simulate MESCs with various configurations and material properties to provide a design guideline of MESCs in multiple applications.
On the Modeling of Wildfires-Induced Release and Atmospheric Dispersion in Radioactively Contaminated Regions
Authors: Polat Damla , Diaconeasa Mihai A. 
Published: January 2022

Abstract
Nuclear energy is one of the most efficient types of electricity production. However, it is one of the biggest fears of people due to the potential radiation effects on human health. Despite the major developments in the nuclear sector, some gaps need to be studied for the higher safety scrutiny of nuclear power plants (NPPs). Besides technical advances for the safer management of an NPP, another important part is having a well-constructed and planned probabilistic risk assessment and management. Realistic probabilistic risk assessment and management provide proper emergency response in case of an accident or hazardous situation to human health. On the other hand, aside from the radiation emitted directly from radioactive sources inside the NPP, there may be indirect radiation emission from dispersions outside the plant’s protected area. For example, we can look at forest fires occurring in radioactively contaminated areas surrounding NPPs that suffered accidents with releases, such as Chernobyl or Fukushima Daiichi. Radioactive particles produced by burning contaminated forests could spread in the air and threaten public health. It has already been observed that fires in forests around Chernobyl can increase the level of radiation in the air. Such events have the possibility to occur in all areas where nuclear facilities are located. The forests contaminated after the Fukushima Daiichi NPP accident, resemble the ones at Chernobyl. This study aims to develop the knowledge for an early sensing and emergency response by doing an atmospheric dispersion modeling and supporting a probabilistic risk assessment for a wildfire scenario in radioactively contaminated areas, such as Chernobyl and Fukushima Daiichi. Also, this study provides a pathway to assessing the risk of nuclear contamination caused by wildfires around nuclear facilities.
Constitutive Modeling and Validation of Sintered Metal Powders Subjected to Large Strains and High Strain Rates
Authors: West Ashby , Venable Garrett , Flanagan Michael , Harris Evan , Davis Brad G. , Davidson F. Todd , Hanus Joseph 
Published: January 2022

Abstract
The development of advanced small caliber weapon systems has resulted in rounds with more material penetration capabilities. The increased capabilities may mean that existing live-fire facilities will no longer be adequate for the training and certification of military and law enforcement personnel, which could result in training constraints and possibly expensive upgrades to improve the safety of existing facilities. New training ammunition manufactured from novel structural materials are needed to allow for the safe, continued use of live-fire shoot house facilities. The goal of this project is to characterize a sintered metal powder and fit a suitable constitutive model for simulation in support of numerical design. A pressed and sintered blend of copper-tin was selected as a suitable representative material for this application. Samples were tested in uniaxial compression under quasi-static conditions and elevated temperatures. Dynamic compression testing at strain rates up to approximately 105 s−1 was conducted using a split-Hopkinson bar. The results of these tests were then used to fit Johnson-Cook and Zerilli-Armstrong strength models to the test data. The models were fit by selecting points from test data at different strain rates and elevated temperatures. This system of equations was then solved for each model while using the same test data to ensure a fair comparison of the results. A Mie-Gruneisen equation of state for the material was estimated using a rule of mixtures and existing shock and particle velocity data. Taylor cylinder tests were conducted and the rate of change in length was measured using high-speed video. Simulation of the Taylor tests was conducted using the developed strength and equation of state model and compared to the experimental results for model validation and comparison. Both the Johnson-Cook and Zerilli-Armstrong models resulted in less than 1% error of the Taylor cylinder results before material fracture. Further development of a fracture model for this material is recommended for use in high strain rate modeling applications.
Design of a 3D Aerospace Bracket Using Lattice Structures and Topology Optimization for Additive Manufacturing
Authors: Ates Gorkem Can , Demirtunç Mehmet , Göçer Ali Cem , Doğru Abdulhamid Han , Gorguluarslan Recep M. , Gökdağ İstemihan , Yavaş Hakan 
Published: January 2022

Abstract
In this study, a design optimization framework is presented that utilizes the topology and lattice structure optimization approaches to design an aerospace component for additive manufacturing (AM). In this framework, the topology optimization is first utilized to find the relative density distribution in the design space of the component that maximizes its stiffness under the volume and strength constraints. The optimized density distribution is used to generate an initial lattice structure topology. A two-step size optimization is also carried out using the beam element formulation in the FEA. The diameters of the strut members in the lattice structure are aimed to be kept within the manufacturability limits of the selective laser melting (SLM) process with AlSi10Mg alloy to satisfy the volume and stress constraints while maximizing the overall stiffness. Optimized designs are determined with four different lattice types. The best design among them is analyzed to ensure an additional natural frequency constraint using modal analysis. Thus, a novel lattice structure design is achieved that satisfies the strength and vibration-specific requirements of the aerospace component for a real-world application. The developed lattice structure design of the aerospace component is achieved with a 30% reduction in weight while still satisfying the desired requirements compared to the existing design in use. The presented lattice design optimization framework is presented in a way that is not application-specific so that it can also be used for the design of different components for AM. The future work includes experimental validation of the strength and vibration performances of the SLM-fabricated design.
Operational Modal Analysis of a Rotating Structure Subject to Random Excitation Using a Tracking Continuously Scanning Laser Doppler Vibrometer via a Two-Dimensional Scan Scheme
Authors: Lyu Linfeng , Zhu Weidong 
Published: January 2022

Abstract
A two-dimensional (2D) scan scheme is developed for a tracking continuously scanning laser Doppler vibrometer (CSLDV) system to scan the whole surface of a rotating structure excited by a random force. A tracking CSLDV system is developed to track a rotating structure and sweep its laser spot on its surface. The measured response of the structure using the 2D scan scheme of the tracking CSLDV system is considered as the response of the whole surface of the structure subject to random excitation. The measured response can be processed by an operational modal analysis (OMA) method called the improved demodulation method based on a rigorous model of a rotating plate to obtain modal parameters of the rotating structure, such as damped natural frequencies and undamped full-field mode shapes. Damped natural frequencies of the rotating structure are estimated from the fast Fourier transform of the measured response. Undamped full-field mode shapes are estimated by multiplying the measured response using sinusoids whose frequencies are estimated damped natural frequencies. Experimental investigation of the 2D scan scheme of the tracking CSLDV system and OMA method is conducted, and damped natural frequencies and undamped full-field mode shapes of a rotating fan blade with different constant speeds are estimated. It is theoretically and experimentally shown that damped natural frequencies of the rotating fan blade increases with its rotation speed.
Reliability Analysis of Flexible PCBs
Authors: Shejwal Amogh , Srivastava Ashutosh , Medikonda Sandeep , Aminjikarai S. Babu 
Published: January 2022

Abstract
Flexible Circuit Boards (FCB) are ubiquitous in most electronic devices used today. These are utilized in mobile phones, display cables in laptops, cameras, smart watches, robotic arms and more. They are mainly used in applications where space, flexibility and construction constraints limit the usage of conventional Printed Circuit Board (PCB). While FCBs offer numerous advantages over traditional PCBs, like enhanced reliability, capabilities, reduced weight, and lesser space utilization, on the other hand, they present different set of challenges like assembly, installation, and difficulty in repairing and reworking after installation. The flexes are generally bent at several points before conforming to the installed state which induces stresses before the actual operation or the working phase. These stresses are further magnified during the cyclic loading which can lead to breakage of these flexes. Due to intricacies involved in FCBs, numerical modeling of these components is challenging.
In this work, a methodology is developed in Ansys Mechanical™ to model the installation and operating phase of the FCB. Stresses generated in both the phases are calculated and fatigue life is computed after the operational phase. Two different models are analyzed. The first model is a Rigid Flex PCB, where a FCB connects with the rigid PCBs. The second model is a standalone FCB cable. For both the models, shell elements are used to mesh the FCBs, which are typically thin structures and experience a large amount of rotation and bending loads. Trace mapping feature is used to accurately model the large number of intricate features such as copper traces, vias and other Electronic-CAD data. The trace mapping feature simplifies the model by modeling the geometry as dielectric layers and includes the effect of traces by mapping the metal fraction onto the dielectric layers.
The loop forming capability of both the models is analyzed where they are subjected to a 180° bend. The fatigue induced due to this bending load is calculated for both the models. For the FCB cable case, the work is extended to study the stresses developed in the installation phase as it impacts the overall fatigue life of the FCB. Here the rigid surface bodies are used to push/deform the FCB cable to its final installation stage. Lastly, a detailed High-Performance Computing (HPC) scalability study is performed in-order to find the best balance between the number of cores and solution time.