bluuebunny/crossref_metadata_2025_split huggingface dataset:
Natural Convection in Yield Stress Fluids From a Confined Horizontal Plate
Authors: Patel S. A. , Raja A. H. , Chhabra R. P. 
Published: January 2020

Abstract
The heat transfer characteristics from an isothermal heated plate in a quiescent yield stress fluid in a cavity was investigated over a wide range of parameters (Rayleigh number, 102 ≤ Ra ≤ 105, Prandtl number, 10 ≤ Pr ≤ 100, and Bingham number, Bn ≥ 0) where the flow is known to be laminar and steady. The coupled momentum and energy equations have solved here numerically within the framework of Boussinesq approximation to capture the temperature-dependent fluid density. The results demonstrate that for a given value of the Rayleigh number, there exists a critical value of the Bingham number, above which the fluid is completely unyielded and heat transfer occurs solely by conduction. In order to delineate the effect of domain geometry on the conduction limit, the study was extended over a range of geometrical aspects by varying the aspect ratio (λ = diameter of the cavity/ a length of the plate), 2 ≤ λ ≤ 5. This work shows that the critical value of the Bingham number can be described as a function of geometry of domain, Ra and Pr. The value of critical Bingham number increases with the increasing aspect ratio and Rayleigh number in order to approach the conduction limit. The yield surfaces show that the increasing values of Rayleigh number induce fluid-like behaviour whereas Bingham number opposes this propensity. The average Nusselt number decreases with the increasing Bingham number due to the suppression of the advective component of heat transfer.
Simultaneous and Iterative Estimation of Vehicle Ride Model States and Parameters
Authors: Sampathraghavan Lakshmi , Ramarathnam Krishnakumar 
Published: January 2020

Abstract
With advancements in vehicle electronics and growing focus on vehicle safety systems, state and parameter estimation has become a remarkable sphere of research. In this study, the vehicle vertical dynamics states and parameters were estimated simultaneously and iteratively with relevant vehicle responses. This was achieved through vehicle tests, designed to excite the corresponding vehicle states. A linear Kalman filter was used for state estimation. Vehicle parameters were obtained as a optimal solution using an optimization algorithm. With the help of multi-DOF vehicle ride model along with real vehicle measurements, the state and parameter estimators work concurrently to obtain the results. A cleat test was performed for a Sports Utility Vehicle (SUV) in IPG CarMaker® and in reality, for evaluation of the proposed framework. The state estimation results showed upto 93% correlation from simulated data and upto 81% correlation from real time measurements. Parameter estimation produced an average error of only 9.1%. This demonstrated the efficacy of the algorithm for use in vehicle systems.
Polychromatic Coloring of Dental Zirconia by Inkjet Printing
Authors: Rehekampff Christoph , Rumschöttel Dominik , Irlinger Franz , Lueth Tim C. 
Published: January 2020

Abstract
To enable the development of an automated coloring process, dental zirconia is examined in terms of porosity, pore size and shrinkage during sintering. The properties of commercially available metal ionic inks such as viscosity, density and surface tension are investigated. Droplet impact on the zirconia surface and the absorption into the pores is analyzed with a high speed camera. The color result after sintering is investigated and compared to tooth samples.
A method is developed to achieve a realistic, smooth color transition on flat zirconia samples. This is achieved by mixing the single inks directly on the zirconia through sequential application. Consequently, the number of different inks required to reproduce the full dental color scale can be reduced. Additionally, three dimensional tooth replacements are colored with the developed method.
Maximizing Energy Harvesting of Photovoltaic Panel Full Tracking Optimization
Authors: Abdelmaksoud Ahmed Y. , A. Hegazi Hesham , El Morsi Mohamed S. , Metwalli Sayed M. 
Published: January 2020

Abstract
The wide spread use of solar energy and photovoltaic solar cells attracts researchers to work hard for the objective of improving their performance to be a viable attractive alternative to fossil fuels. This work presents the optimization of the output power of a photovoltaic solar cell to harvest maximum power. The power is optimized based on PVP full tracking of the sun and the effect of the tilt, the azimuth, and the incidence angles on its performance. A meta-model is utilized as a tool in the optimization technique. A case study which develops 2nd, 3rd, and 4th order hyper-surface equations that depend on day and hour to get the optimum tilt angle and optimum azimuth angle for the city of Hurghada in Egypt. The power produced from the polynomial meta-model algorithm is higher by 25.5% over the fixed tilt and azimuth angles. The developed equations from the meta-model optimization technique can be used in tracking control systems to get optimum tilt and optimum azimuth angles at any hour and at any day. By comparing the metamodel and the lengthy performance optimization technique, the error is around 1.1%. Comparison has also been made between the cost of the fixed and full tracking photovoltaic systems.
A New Mobile Anti-Ramming System
Authors: Baragetti Sergio , Arcieri Emanuele Vincenzo 
Published: January 2020

Abstract
The recent vehicle-ramming terror attacks in Berlin, Barcelona, London and Nice pointed out our vulnerability: all of us could be victims during a walk in our squares or in crowded places, it is sufficient a car, a van or a truck.
The current solution to this problem is the application of concrete barriers in our cities. These devices are not good-looking and give a sense of danger to the human beings. But are they effective?
Starting from this question, the authors studied the effectiveness of these barriers and developed a new good-looking mobile device.
The study was carried out by means of mathematical and numerical models. In particular, a spring-mass system was used in order to macroscopically represent the problem and finite element analyses by explicit calculation in Abaqus were carried out. Also Smoothed Particle Hydrodynamics (SPH) method was used in the numerical models.
The final shape of the barrier is a planter full of water which is urban furniture and anti-ramming system at the same time. The barrier is made of metal, without foundation and characterized by high friction coefficient between the ground and the barrier itself and a good mass distribution, studied to stop the vehicle in few meters.
The high deformability and the ability of the water in the barrier to take away a lot of energy allow to stop a 3500 kg vehicle running at 64 km/h and the system itself in less than four meters as demonstrated by the crash test carried out. As consequence of this crash test, the anti-ramming system is IWA 14-1:2013 and PAS 68:2013 certificated.
Membrane Fouling Mitigation in Water Filtration Using Piezoelectrics
Authors: Aronu Obinna , Abramowitz Harvey , Nnanna Agbai George 
Published: January 2020

Abstract
The clogging of filtration membrane by particles otherwise known as fouling is a major concern in membrane filtration technology due to severe flux reduction associated with it, which results to the reduction of membrane lifespan, reduced system performance and increased process and operating costs in industries that utilize membrane in their production process. This is because the cleaning or replacement of the fouled membrane requires production to be interrupted for the cleaning process or the entire system to be shut down for the replacement process to take place, leading to great loses to the industries involved. Many approaches have been devised over the years through research to tackle this problem, some of which not only undermine the performance of the filtration membrane but also contribute to great loses to industries that apply them. Cheaper and more efficient means of fouling control remains the key to salvaging this problem. This work proposes a water filtration system in which piezoelectric crystals attached at strategic points on a tubular polyvinylidene fluoride (PVDF) membrane are used to increase flux and delay the clogging of the pores of the filtration membrane by particles during water filtration. Filtration tests with mud solution show that the membrane vibrated with piezoelectrics reduced the clogging of the pores and increased permeate flux of the filtration process as compared with the case where the membrane was not vibrated with piezoelectrics, suggesting that vibrating the system with piezoelectrics is a good fouling reduction method that can be used in fluid separation processes. To optimize the permeate flux production of the system and fouling reduction, the anti-fouling effects of the piezoelectric crystals on the membrane surface is investigated through experiments together with the effects of voltage application, positioning and placement distance of the piezoelectrics and some other variables involved in this work.
An Application of a Digital Twin to Robotic System Design for an Unstructured Environment
Authors: Marshall Matthew Q. , Redovian Cameron 
Published: January 2020

Abstract
An experimentable digital twin is created to aid in a design decision (beginning of life stage) for a robotic system. This product is meant to automate a material-feed system. The robot comprises a six-axis manipulator mounted on a mobile base. Due to variability in the dimensions of the material-feed system and positioning error of the mobile base, the material-placement routine is considered to take place in an unstructured environment. Working therein requires exteroceptive sensors, in this instance taking the form of computer vision. Data from this subsystem are used to match the geometry of the digital twin to the physical environment. This close correspondence between physical and virtual embodiments allows for significant design decisions to be reached from simulated experiments. In this case, two motion-planning approaches are compared and it is determined that the costs associated with implementing the dynamic one in the lab for testing are merited by its ease of use and reliability, since simulation-based control employs all current information.
Low Frequency Absorption of Additively Manufactured Cylinders
Authors: Kaye Sophie R. , Casavant Ethan D. , Slaboch Paul E. 
Published: January 2020

Abstract
Attenuating low frequencies is often problematic, due to the large space required for common absorptive materials to mitigate such noise. However, natural hollow reeds are known to effectively attenuate low frequencies while occupying relatively little space compared to traditional absorptive materials. This paper discusses the effect of varied outer diameter, and outer spacing on the 200–1600 Hz acoustic absorption of additively manufactured arrays of hollow cylinders. Samples were tested in a 10 cm diameter normal incidence impedance tube such that cylinder length was oriented perpendicular to the incoming plane wave. By varying only one geometric element of each array, the absorption due to any particular parameter can be assessed individually. The tests confirmed the hypothesis that minimizing cylinder spacing and maximizing cylinder diameter resulted in increased overall absorption and produced more focused absorption peaks at specific low frequencies. Wider cylinder spacing produced a broader absorptive frequency range, despite shifting upward in frequency. Thus, manipulating these variables can specifically target absorption for low frequency noise that would otherwise disturb listeners.
Fully Transient Model of a Hydraulic Accumulator
Authors: Kratschun Filipp , Rambaks Andris , Schmitz Katharina 
Published: January 2020

Abstract
Hydraulic piston accumulators play a major role especially within the field of stationary hydraulics. The calculation of the amount of hydraulic energy which can be stored in such an accumulator is crucial when it comes to a precise system design. The knowledge of the temperature within the accumulator is required in order to calculate the amount of energy to be stored.
This paper presents a simulation approach with the goal to simulate the gaseous phase within a piston accumulator and to present results for the polytropic exponent without conducting costly experiments. The temperature, pressure, density and velocity profiles inside of the gaseous phase as well as the temperature profile inside the boundaries are calculated transiently in order to achieve that goal.
The effects of dissipation, heat transfer and transient wall temperature are added to the simulation routine continuously and their effects on the results are discussed in detail.
Pressure Drop in Circular Two-Phase Pipe Flow As Influenced by the Angle of Inclination
Authors: Worl Bethany , Nielson Samuel , Wang Xiuling 
Published: January 2020

Abstract
A variety of models exist to describe the frictional pressure drop for two-phase flow in a pipe. These models all are based on assumptions and simplifications of the flow regime and can experience difficulty when modeling flow through non-horizontal pipes due to the buoyant effects as the bubbles grow in size. Using computational fluid dynamics, it is possible to model the interaction between the two phases and determine an expected pressure drop. In order to evaluate the effect of the inclination angle of a channel, a parametric study will be conducted using ANSYS Fluent; these predicted pressure drops will then be compared to those found in literature for validation and then to other theoretical pressure drop calculations. Through this study, the benefits of both the theoretical framework and the numerical simulation will be identified.
Exergy Analyses of a Solar-Biogas Hybrid Micro Gas Turbine for Power Generation
Authors: Alshahrani Saad , Engeda Abraham 
Published: January 2020

Abstract
Solar thermal power is considered one of the most promising renewable energy resources that has witnessed a great technological improvement in the last two decades. Saudi Arabia has very intensive solar radiation because it is located in the sun belt region, which has led it to become one of the largest solar energy producers. In this paper, detailed exergy analysis of a solar-biogas hybrid micro gas turbine for power generation is presented. The system is driven by a central receiver and biogas as backup based on the hybridization technique. The net power output of the system is set to 100 kW. This study demonstrates that the highest exergy destruction occurs in the recuperatore and ceramic heat exchanger, about 22.6% and 22.5%, respectively, and that is due to the high entropy generation and the irreversibilities in these components. Moreover, the exergy destruction for all system components was examined at different environment temperatures. The study revealed that the exergy destruction for compressor, regenerator, and receiver decreases with an increase in the environment temperature, but the exergy destruction increases for turbine and heliostats field.
Heat Transfer Induced by Electron Tunneling Between Two Metal Plates
Authors: Yao Bojing , Pan Liang 
Published: January 2020

Abstract
We calculated the heat transfer caused by electron tunneling between two semi-infinite metal plates separated by a vacuum gap, which are made of the same material. The tunneling of electron is described by one dimensional quantum tunneling and its transmission coefficient. Sommerfeld model is used to derive the math expression of electron motion. Based on calculation results, we find that when the gap distance is below 1 nm, electron tunneling induced heat transfer starts to be considerable, which could exceed near-filed radiative heat transfer.
Acoustic Control of a Maneuverable Marine Hydrokinetic Cycloturbine
Authors: Goldschmidt Margalit Z. , Jonson Michael L. , Horn Joseph F. 
Published: January 2020

Abstract
Marine Hydrokinetic (MHK) cycloturbines exploit tidal currents to generate sustainable electric power. Because of the harsh marine environment, MHK cycloturbines require frequent maintenance and repair, which for current systems necessitates the use of a ship, making the process difficult and costly. A novel MHK cycloturbine system has been designed that uses pitching foils for maneuver, potentially circumventing the costs and difficulties associated with deployment and repairs. The vehicle fatigue is decreased and the vehicle’s acoustic signature underwater is reduced by design of a novel acoustic controller. This controller specifically reduces the tonal noise at blade rate frequency.
Each turbine foil radiates noise equivalent to an acoustic dipole at multiples of blade rate frequency, and so the vehicle is modelled as an acoustic multipole. At blade rate frequency, the turbine size compared to its acoustic wavelength allows for the entire vehicle to be treated as a compact source. The effect of turbine clocking on directivity and sound power is shown. The effects of the designed controller to reduce tonal noise at blade rate frequency and multiples are verified experimentally through testing in ARL’s Reverberant Tank facility. Fixing a Subscale Demonstrator (SSD) to a reaction frame provides the ability to measure the integrated loads using load cells. The radiated sound pressure is computed for the load cell data obtained. Acoustic control is implemented using the turbine RPM: turbines are clocked by slowing one turbine relative to another for a short period of time.
Computational Model for Knowledge Transfer Skills in Industry 4.0 in an Enhanced and Effective Way
Authors: Artifice Andreia , Luis-Ferreira Fernando , Sarraipa João , Jardim-Goncalves Ricardo 
Published: January 2020

Abstract
The current swift pace of development is a reality that is crossing many domains in society demanding specific measures to cope with such scale of development. In the new paradigm of Industry 4.0, new competences and professional skills are needed in the most diverse quadrants of society. The importance of adequately adapt the societal systems and to promote the adequate skills is worth as much as the value we give to present and future generations. Among demanding challenges arising from this changing reality, the transfer of knowledge from academia to industry is probably the most demanding. This reality is present across diverse countries and continents and for that, pilot deployments and lessons learned should be documented and shared to promote better and effective skill development. In this context, the SHYFTE project is establishing a computational model for knowledge transfer skills in industry 4.0.
A Biomass Supply Chain Optimization Framework With Linear Approximation of Biomass Yield Distributions for Improved Land Use
Authors: Cooper Nathanial , Panteli Anna , Shah Nilay 
Published: January 2020

Abstract
Biomass and the bio-economy have strong potential to help shift dependency away from petroleum. Supply chain optimisation (SCO) has been used to help other industries and can be used to boost biomass industry viability. Biomass supply chain models frequently average the biomass yield of large tracts of land in their calculations. However, there can be large variation in the biomass yield within those tracts, losing useful information. This work presents a biomass SCO framework which approximates the available quality of land by piecewise linearly approximation of the biomass yield distribution, and incorporates this information into the optimisation. The linear estimates of the biomass yield distributions allow the SCO model to make more informed decisions about quantity and location of biomass growth operations, affecting all downstream decisions. A case study of mainland Great Britain has been examined using the framework to illustrate the impact of retaining biomass yield information in the optimisation, versus averaging the yield across tracts of land. The case study found that using biomass yield linear estimates reduced the overall land usage by 10%. Further, it improved biomass output, which increased the quantity of bio-products produced. All of this led to an increase in the overall profit.
Bone-Integrated Optical Microlasers for In-Vivo Diagnostic Biomechanical Performances
Authors: Cavazos Omar , Manzo Maurizio , Ramírez-Cedillo Erick , Siller Hector R. 
Published: January 2020

Abstract
Bones experience mechanical loads on a daily basis. It is difficult to obtain biomechanical performances in-vivo measurements. When implants are integrated with bones after surgery, especially in aged individuals, their osseointegration can compromise the structural integrity of bones; for this reason, it is important to monitor the evolution of the mechanical properties of bones with some in-vivo diagnostic technique. In this study, we propose to integrate optical microsensing devices into bones. To simulate the working principle, a sensor is integrated with a 3-D printed bone. The sensing element is a dye-doped optical microlaser based on the morphology dependent resonance (MDR) shifts also called the whispering gallery mode phenomenon (WGM). When the microlaser is excited by a light source, the fluorescence from the dye couples with the optical resonances. These optical resonances are very sensitive to any perturbation of the microlasers’s morphology. Therefore, the local strain variation of the bone can be related to the shift of the optical resonances. This in-vivo technique monitors the biomechanical performance of bones with implants and prosthetics.
Numerical Analysis of Charging Process of a Shell and Tube Latent Heat Thermal Energy Storage System With PCM Embedded in Highly Conductive Porous Material
Authors: Mahdavi Mahboobe , Tiari Saeed , Sawyer Carley 
Published: January 2020

Abstract
The purpose of this study was to ascertain the effects of impregnation of porous material with the PCM on the thermal performance of a shell and tube latent heat thermal energy storage system. The heat transfer fluid flows in the tube while the phase change material is stored in the shell. A transient numerical model was developed to simulate the charging process of the system. The effects of porous material filling ratio, and its properties such as porosity and permeability, were studied on the performance of the system. The results showed that the porosity of the material or the metal foam has the greatest effect on the heat transfer and charging time of the system specifically for a filling ratio of one, or when the entire annular gap between the inner and outer tube is filled with the metal foam. As the filling ratio decreases, the effect of the porosity decreases; however, there is no linear relationship between the filling ratio and the decrease in the melting time as the porosity changes.
Discovery of Public Transportation Patterns Through the Use of Big Data Technologies for Urban Mobility
Authors: Antunes Hugo , Figueiras Paulo , Costa Ruben , Teixeira Joel , Jardim-Gonçalves Ricardo 
Published: January 2020

Abstract
Big cities show a wide public transport network that allows people to travel within the cities. However, with the overcrowding of big urban areas, the demand for new mobility strategies has increasing. Every day, citizens need to commute fast, easily and comfortable, which is not always easy due to the complexity of the public transport network. Therefore, this paper aims to explore the ability of Big Data technologies to cope with data collected from public transportation, by inferring automatically and continuously, complex mobility patterns about human mobility, in the form of insightful indicators (such as connections, transshipments or pendular movements), creating a new perspective in public transports data analytics. With special focus on the Lisbon public transport network, the challenge addressed by this work, is to analyze the demand and supply side of transportation network of Lisbon metropolitan area, considering ticketing data provided by the different transportation operators, which until now were essentially obtained through observation methods and surveys.