bluuebunny/crossref_metadata_2025 huggingface dataset:
Hands-On Experiences for Problem Solving in Engineering Education Based on Trees and Plants
Authors: Vargas-Silva Gustavo , Jawaharlal Mariappan
Published: January 2019

We teachers know that problem solving is a crucial skill for our students. It is indispensable for developing original and creative thinking. We also know that deep learning of engineering fact can be assisted by using non-conventional tools and heterodox ideas for teaching, learning and presenting technical concepts. On that sense, we propose that engineering students could learn how to solve hands-on problems from nature; in particular from the plant kingdom.

In addition, we engineers should not turn our back to nature. We should start a new voyage of discovery, seeking new landscapes with a different outlook. But how? The present paper presents an approach to integrate trees and plants into engineering education to learn problem solving hands-on experiences. The aim of this approach is to teach engineering design using trees in the local area with an emphasis on structural strategies. Students taking courses such as statics, dynamics, strength of materials, stress analysis, material science, and design courses can benefit tremendously from studying trees. Furthermore, this approach provides an exciting opportunity for students to understand the complexities of real world living systems, appreciate the genius of nature’s design, and develop methods to create sustainable designs.

We think that those kind of natural realistic problems are complex: they have conflicting objectives, multiple solution methods, non-engineering success criteria, non-engineering constraints, unanticipated issues, interactions, collaborative activity systems, and multiple forms of problem representation. From an educational point of view, using a tree can bring tremendous practical benefits for problem solving in engineering education. Trees are everywhere, and they can easily integrate them into the classroom. Trees offer unlimited potential for teaching and research. For example, each student will have a different tree, and there are plenty of them, so each problem will be original and creative for each student providing a genuine learning experience.

The present work puts on view a new development for teaching structural mechanics based on plant biomechanics, i.e. the study of the structural strategies of plants (and trees). The goal is to understand and emulate structures and functions of the plant kingdom to develop structural solutions in engineering. Therefore this paper presents teaching results and novel concepts for problem solving in engineering education, seeking new landscapes.
Control Analysis of a 3D Self-Balancing Inverted Pendulum and Cart System for Stability in the Event of a Sensor Failure
Authors: Lamb Sarah , Mellodge Patricia , Sohn Kiwon , Tatoglu Akin
Published: January 2019

This paper studies and simulates the dynamics and controls for a two-wheeled robotic chassis that successfully and consistently self-balances. Previous approaches to similar models have derived their dynamics from first principles using Newtonian mechanics for a linearized, shared-axle system and Lagrangian mechanics for a linearized, independently-actuated system. As such, the derived dynamics do not often reflect important factors of real world models which are not linear. However, this study specifically focuses on a more complicated system with independently-actuated wheels, for which a sophisticated and realistic dynamic model is derived using non-linearized Lagrangian mechanics. The pendulum and cart movements are each assumed to be planar, and their planes of motion are defined perpendicular to each other. The system’s performance is then analyzed in the simulation environment to determine the effect of various controllers and filters in cases of full and partial state feedback with and without sensor noise. Performance is characterized in terms of pendulum angle relative to the vertical axis and cart trajectory relative to the ground plane, both of which are functions of the voltage-applied force on each wheel independently. A comparison of the results shows that the non-linearized Lagrangian model best fits the true data and yields less uncertainty given a sensor failure. Therefore, the presented study has high intellectual merits compared to existing studies which focus on only linearized models. Based on the deterministic parameters of this study’s non-linearized model, a recommendation is made about which combination of controllers and filters best maintains the system’s stability in the event of a sensor failure returning only partial state feedback.
Test Results: Vehicle Responses to Simulated Drag Caused by Front Tire Tread Detachment — The Effect of Scrub Radius and Speed
Authors: Arndt Mark W. , Arndt Stephen M.
Published: January 2019

The effects of reduced kingpin offset distance at the ground (scrub radius) and speed were evaluated under controlled test conditions simulating front tire tread detachment drag. While driving in a straight line at target speeds of 50, 60, or 70 mph with the steering wheel locked, the drag of a tire tread detachment was simulated by applying the left front brake with a pneumatic actuator. The test vehicle was a 2001 dual rear wheel four-wheel-drive Ford F350 pickup truck with an 11,500 lb. GVWR. The scrub radius was tested at the OEM distance of 125 mm (Δ = 0) and at reduced distances of 49 mm (Δ = −76) and 11 mm (Δ = −114). The average steady state responses at 70 mph with the OEM scrub radius were: steering torque = −24.5 in-lb; slip angle = −3.8 deg; lateral acceleration = −0.47 g; yaw rate = −8.9 deg/sec; lateral displacement after 0.75 seconds = 3.1 ft and lateral displacement after 1.5 seconds = 13.1 ft. At the OEM scrub radius, responses that increased linearly with speed included: slip angle (R2 = 0.84); lateral acceleration (R2 = 0.93); yaw rate (R2 = 0.73) and lateral displacement (R2 = 0.59 and R2 = 0.87, respectively). At the OEM scrub radius, steer torque decreased linearly with speed (R2 = 0.76) and longitudinal acceleration had no linear relationship with speed (R2 = 0.09). At 60 mph and 70 mph for both scrub radius reductions, statistically significant decreases (CI ≥ 95%) occurred in average responses of steer torque, slip angle, lateral acceleration, yaw rate, and lateral displacement. At 50 mph, reducing the OEM scrub radius to 11 mm resulted in statistically significant decreases (CI ≥ 95%) in average responses of steer torque, lateral acceleration, yaw rate and lateral displacement. At 50 mph the average slip angle response decreased (CI = 87%) when the OEM scrub radius was reduced to 11 mm.
Simulation of Fluid Flow in a Microchannel at Low Reynolds Number Using Dissipative Particle Dynamics
Authors: Waheed Waqas , Alazzam Anas , Al Khateeb Ashraf N. , Abu Nada Eiyad
Published: January 2019

In this paper, a two-dimensional Dissipative Particle Dynamics (DPD) technique to simulate the poiseuille flow in a microchannel is developed using an in-house code. The calculated Reynolds number is reduced via adjusting the DPD parameters. The obtained velocity profile is compared with the analytical results and a good agreement is found. The drag force and the drag coefficient on a stationary cylinder exerted by the fluid particles are obtained using the developed DPD code. The calculated drag coefficient exhibits a close match with already published data in the literature.
Evaluation of Transverse Shear Moduli of Composite Sandwich Beams Through Three-Point Bending Tests
Authors: Şener Özgün , Dede Oğuzhan , Atalay Oğuz , Atasoy Mert , Kayran Altan
Published: January 2019

Transverse shear moduli of the sandwich core and flexural stiffness of all-composite sandwich constructions are determined with three-point beam bending tests, and compared with the analytical and finite element analysis solutions. Additionally, Digital Image Correlation (DIC) system is employed to validate the experimental results by monitoring the displacements. The effect of orientation of the composite core material with respect to the beam axis on the shear modulus of the core material itself, flexural stiffness of the sandwich beam, maximum loading, and the maximum stresses on the sandwich panel are also examined. Comparable results are achieved through experiments, finite element and analytical analyses.
Gait Analysis for Muscular Forces Evaluation in Human Movement: Integration Protocol of Typical Measurement Methods
Authors: Fontanili Luca , Milani Massimo , Montorsi Luca , Valente Giordano
Published: January 2019

The paper focuses on the gait analysis for the investigation of the typical events occurring in human movements and validate its use as a method for musculoskeletal disease evaluation and for the improvement of athletic training. In the present research the motion capture system is combined with an in-house developed prototype of uniaxial force plates for the measurement of the vertical component of ground reaction forces during movement.

While similar techniques are implemented for gait, this equipment can be employed to investigate running, thus, covering a larger number of possible applications and providing a deeper insight either of the athlete performance or the disease analysis.

For the prevention and the treatment of those events occurring during running, a thorough understanding of its mechanisms is critical; therefore, a method for evaluating both the kinematic behavior of the human body and the ground reaction forces combined to a model for determining the muscle forces is proposed.

An infrared motion capture technique is adopted for measuring accurately the body motion and a multiple force-plate system is used to calculate the force exerted by the ground and sub-divided in the three components by an ad-hoc developed routine.

Moreover, the data are used as input parameters for the OpenSim software to derive muscles forces. Finally, the potential of the proposed protocol is determined by an experimental campaign on healthy subjects and a significant database of muscle forces is constructed for different running speeds.
Reconstruction of Swirling Blood Flow in the Heart and Aorta on the Basis of Measurements of Dynamic Geometry and Elastic Properties of the Flow Channel
Authors: Talygin Eugeny A. , Zhorzholiani Shota T. , Tkhagapsova Marina M. , Tsygankov Yuriy M. , Agafonov Andrei V. , Gorodkov Alexander Y. , Kiknadze Gennadiy I. , Bockeria Leo A.
Published: January 2019

As it has been shown previously, the blood flow in the heart and the main vessels is a self-organizing tornado-like flow of a viscous fluid, exhaustively described by the particular solution of nonstationary hydrodynamic equations coined in 1986. This solution is implemented in a local dynamic cylindrical coordinate system, which origin moves with the flow. Streamlines of these flows are characterized with an axial symmetry and determine certain restrictions to the geometry of the flow channels. It has been proved, that the experimentally measured orientations of intraventricular trabeculae and dynamic geometric characteristics of the aortic flow channel during the cardiac cycle satisfy the conditions for the self-organization of tornado-like blood flow. This enables to obtain relative estimates of the flow parameters using the geometric characteristics of the flow channel. For this, a set of experimentally measured quasi-invariant anatomical marks was used, which static and dynamic parameters are utterly determined by the structure of the dominant blood jet. Such marks are the position of the embouchures of pulmonary veins and the left atrium auricle, the directions of the trabecular profile on the left ventricle streamlined surface, the dynamic geometry of the mitral and aortic valves, the length and radial elasticity of the aorta, etc. These marks allow a formal localization of the dynamic coordinate system position of a swirling blood flow in the investigated part of the cardiovascular channel and more accurate estimation of the jet structural parameters evolution.

Basing on these parameters, a consistent theory of the initiation and evolution of swirling blood jet in the flow channel beginning from the left atrium to the aorta and its main branches has been proposed. The result of the study is a concept, integrating the measured characteristics of the heart and the aorta flow channel (dynamic dimensions, elasticity) and the structural parameters of swirling blood flow. It was shown that flow channel pathological changes significantly affect the flow structure.
Virtual Experimental Investigation for Industrial Robotics in Gazebo Environment
Authors: Aksu Murat , Michaloski John L. , Proctor Frederick M.
Published: January 2019

Measuring the agility performance of the industrial robots as they are performing in unstructured and dynamic environments is a thought-provoking research topic. This paper investigates the development of industrial robotic simulation algorithms for the effective application of robots in those changing environments. The distributed framework for this investigation is the Robot Operating System (ROS) which is extensively used in robotic applications. ROS-Industrial (ROS I), which extends the capabilities of ROS to manufacturing, allows us to interoperate between industrial robots, sensors, communication buses and other kinds of automation tools. Gazebo is used as the open-source 3D simulator to design a virtual industrial robotic system, which is a prevailing tool as a node in the ROS environment. An effort is underway to replicate the in-house experimental robotic kitting lab with a graphical physics simulation that can be shared worldwide. This graphical physics simulation is not tied to a specific robotic control system. An experimental approach will be presented detailing the issues related to a physics based simulation of kitting with multiple collaborative robots, multiple tools, parts, tool changers, safety system, and sensors. In this realm, the ability for the simulation environment to encompass the current system as well as additional more complex sensors and actuators will be discussed. To make this simulation environment more realistic, Gaussian noise will be introduced to the data generated by virtual sensors. We expect that this experimental approach will be a seamless way for users to verify and validate their control systems even if they do not have a physical robot at their facilities.
Towards a Digital Twin for Cloud Manufacturing: Case Study
Authors: Ngo Diane , Guerra-Zubiaga David A. , González-Badillo Germánico , Vatankhah Barenji Reza
Published: January 2019

Cloud manufacturing (CMfg) is a new manufacturing paradigm designed to enable manufacturing enterprise to share their resources and capabilities. Prior to any real-life change in the system, for CMfg it is important to anticipate and optimize the response of the system through simulation. Digital Twins (DT) is a simulation method for this paradigm that is different from existing simulation methods in two ways. It is a virtual copy of the system containing all the components and can connect to the controller in real time. The goal of this work is to develop a DT for an educational manufacturing cell. The educational manufacturing cell is a FESTO Reconfigurable Mechatronics System (RMS). The cell has four stations that uses pallets to transport the product on the conveyor belt and assembles a part of the product. The Siemens Process Simulate: TECNOMATIX, was used to create the DT of the system. The system is modeled in a CAD program and then imported into TECNOMATIX Process Simulate, where it is programmed to replicate the processes.
Functionalized Cellulose Nanocrystals for Improving the Mechanical Properties of Poly(Lactic Acid)
Authors: Shojaeiarani Jamileh , Bajwa Dilpreet
Published: January 2019

Biopolymers are emerging materials with numerous capabilities of minimizing the environmental hazards caused by synthetic materials. The competitive mechanical properties of bio-based poly(lactic acid) (PLA) reinforced with cellulose nanocrystals (CNCs) have attracted a huge interest in improving the mechanical properties of the corresponding nanocomposites. To obtain optimal properties of PLA-CNC nanocomposites, the compatibility between PLA and CNCs needs to be improved through uniform dispersion of CNCs into PLA. The application of chemical surface functionalization technique is an essential step to improve the interaction between hydrophobic PLA and hydrophilic CNCs. In this study, a combination of a time-efficient esterification technique and masterbatch approach was used to improve the CNCs dispersibility in PLA. Nanocomposites reinforced by 1, 3, and 5 wt% functionalized CNCs were prepared using twin screw extrusion followed by injection molding process. The mechanical and dynamic mechanical properties of pure PLA and nanocomposites were studied through tensile, impact and dynamic mechanical analysis. The impact fractured surfaces were characterized using scanning electron microscopy. The mechanical test results exhibited that tensile strength and modulus of elasticity of nanocomposites improved by 70% and 11% upon addition of functionalized CNCs into pure PLA. The elongation at break and impact strength of nanocomposites exhibited 43% and 35% increase as compared to pure PLA. The rough and irregular fracture surface in nanocomposites confirmed the higher ductility in PLA nanocomposites as compared to pure PLA. The incorporation of functionalized CNCs into PLA resulted in an increase in storage modulus and a decrease in tan δ intensity which was more profound in nanocomposites reinforced with 3 wt% functionalized CNCs.
Fluid-Structure Interaction of Blood Flow in Human Aorta Under Dynamic Conditions: A Numerical Approach
Authors: Martelli Francesca , Milani Massimo , Montorsi Luca , Ligabue Guido , Torricelli Pietro
Published: January 2019

The paper proposes a numerical approach for the analysis of the blood flow in human aorta under real operating conditions. An ad-hoc procedure is developed for importing the aorta geometry from magnetic resonance imaging in order to have a patient based analysis. The aortic flow is simulated accounting for the dynamic behavior of the flow resulting from the heart pulse and for the non-Newtonian properties of blood. Fluid – structure analysis is carried out to address the mutual influence of the flow transient nature and the aorta walls’ deformation on the pressure flow field and tissue’s stresses. Finite element method approach is used for the structural analysis of the aorta walls which are assumed as a linear elastic isotropic material; nevertheless, different regions are introduced to account for the Young modulus variation from the ascending aorta to the common iliac arteries. Mesh morphing techniques are adopted to simulate the wall deformation and a two equation turbulence model is adopted to include the turbulence effects.

The proposed numerical approach is validated against the measurements carried out on magnetic resonance imaging scanner and a good agreement is found in terms of aorta wall maximum and minimum deformation during the cardiac cycle. Therefore, the fluid-structure analysis can provide an important tool to extend the insight of the aortic system from magnetic resonance imaging techniques and improve the understanding of arteriosclerosis and the related phenomena as well as their dependence on flow structure and tissue stresses.
The Virtual Cam – Hexagon Method Authentication on Locating Key Instant Centers of All Planar Single Degree of Freedom Kinematically Indeterminate Linkages up to Ten-Bar
Authors: Liu Zhengqi , Chang Yin-ping
Published: January 2019

At this moment all the methods which had been proposed have extremely limited application to only several specific constructions of kinematically indeterminate linkages, i.e. their complete sets of instant centers cannot be obtained simply from Kennedy Theorem due to lack of enough four-bar loop information in their constructions. Planar single degree of freedom linkages up to ten-bar include two different types of mechanisms, i.e. pure bar linkages, such as four-, six-, eight-, and ten-bar; and geared-bar linkages, i.e. geared-five, seven, and nine-bar. The huge varieties of different types and constructions can serve as great testbeds for these methods. This research systematically investigates and modifies the graphical approach, i.e. virtual cam method, whose employment will show it to be an almost-universal method which can be compliantly applied on very wide range of kinematically indeterminate linkages. The procedures and criteria of the methodology are proposed and examined thoroughly to help locate key instant centers of all planar single degree of freedom kinematically indeterminate linkages up to ten-bar so that their complete sets of instant centers can be located successfully. We call this modified and improved technique as Virtual Cam – Hexagon Method. The results are verified carefully against traditional Kennedy Theorem approach and CAD modeling.
Computational Investigation of Flow Over Geometry Compliant Lattice Structures
Authors: Tinsley James J. , Vernon Gregory J. , Homan Kelly O.
Published: January 2019

With the increasing prevalence of additive manufacturing, geometries that would not have been possible to manufacture just a few years ago are becoming a reality. One example is the ability to create pipes with integral, geometry compliant lattice structures. These compliant lattice structures offer the potential to greatly enhance heat transfer in arbitrary flow passages. This preliminary paper will focus on the development of an isothermal simulation model in OpenFOAM, to model the nature of the flow for a single unit cell, a unit cell screen, and a series of unit cell screens.

Honeywell FM&T is a contractor of the U.S. Government under Contract No. DE-NA0002839.
Behavior of Soft 3D-Printed Auxetic Structures Under Various Loading Conditions
Authors: Ardebili Mahmoud K. , Ikikardaslar Kerim Tuna , Chauca Erik , Delale Feridun
Published: January 2019

Auxetic structures exhibiting non-linear deformation are a prevalent research topic in the material sciences due to their negative Poisson’s ratio. The auxetic behavior is most efficiently accomplished through buckling or hinging of 3d printed structures created with soft or flexible materials. These structures have been hypothesized to have some unique characteristics and may provide advantages over conventional engineering materials in certain applications. The objective of present study is to gain a better understanding of behavior of auxetic structures subjected to tensile, compressive and impact loads and assess geometric parameters affecting these structures in applications such as impact shielding or biomedicine. Analytical and experimental methods were employed to investigate two different types of auxetic structures which were 3d-printed with TPU (thermoplastic polyurethane). The first was based on symmetric re-entrant angles cells patterned to form sheet-like structure. Rotation of members in opposite directions in a cell induces negative Poisson’s ratio when the structure is subjected to tensile loading. The second structure was based on rectangular lattice of circular holes. This structure exhibited auxeticity due to formation of pattern of alternating mutually orthogonal ellipses when subjected to compressive and impact loads.

Parameters of interest in this study included hardness of the plastic used in printing the structures, the fill pattern of 3d-printed solid parts, porosity of cylinders in the lattice structure, angles and thickness of members in the re-entrant structure. Preliminary results indicated that per unit weight of material, the re-entrant structure requires less tensile load to strain than a solid structure. This is advantageous in applications where expansion in lateral direction is required. The lattice of circular holes structure exhibited similar trend in impact and compressive loading. The results indicate that geometric parameters influence auxeticity of the structure a great deal. When the porosity of the lattice is too small, positive Poisson’s ratio is observed. The length to height ratio of the re-entrant cell has similar effect on the structure’s Poisson’s ratio. The main advantage gained by employing such structures is their overall ability to resist buckling and withstand impact load without cracking. This study will help to develop 3D-printing techniques in manufacturing better performing structures under similar conditions.
Elasto-Plastic Modeling of Beams for Impedance Based Structural Health Monitoring
Authors: Sepehry Naserodin , Bakhtiari-Nejad Firooz , Zhu Weidong
Published: January 2019

The structural health monitoring by piezoelectric wafer active sensor (PWAS) using electromechanical impedance method used for monitoring of structure. In present work impedance method of elasto-plastic beam structure is studied. In order to model the effect of a plastic in beam, the moment-curvature relationship for elasto-plastic region for loading and unloading is used. The finite difference method is used to discretize beam with piezoelectric. The piezoelectric actuator is modeled by equivalent moment. Then output current of piezoelectric sensor is calculated. Firstly, elastic modeling of beam is considered that this is leads to linear system equation. In linear system, time domain system equations are calculated and Fourier transform of current output obtained, and then impedance of PWAS in frequency domain is calculated. Secondly, the elasto-plastic of beam is modeled. This phenomenon leads to the nonlinear system equations. These nonlinear equations are solved using finite difference method for any harmonic voltage applied to actuator. Then impedance of PWAS is calculated. Two methods are used to detect elasto-plastic modeling on PWAS impedance. At the first, frequency response of elastic beam as intact model is compared with elasto-plastic results in a desired frequency range. Second, only frequency response of one harmonic is computed with its super-harmonics. Finally, the detection method of linear is compared with nonlinear model.
Considerations for Communications Systems in Underground Refuge Alternatives
Authors: Damiano Nicholas W. , Zhou Chenming , Whisner Bruce
Published: January 2019

In 2008, the Mine Safety and Health Administration (MSHA) published a final rule on Refuge Alternatives (RAs) for Underground Coal Mines. The rule states that RAs shall be capable of sustaining trapped miners for 96 hours and that RAs can also be used to facilitate escape by sustaining trapped miners until they receive communications regarding escape options. As of 2014, there were three types of coal mine RAs manufactured by 10 different companies and at least 13 different communications systems approved for use underground. However, there is no specific guidance on how to determine if such a wide variety of systems will facilitate successful communication in an emergency. Examples in this study detail one representative example of each of the three types of RAs. Each example RA was tested underground in an experimental coal mine by researchers from the National Institute for Occupational Safety and Health (NIOSH). The purpose of the testing was to determine a representative signal attenuation caused by a specific RA’s wall material and entrance door. For each RA type, the signal loss was investigated using comparative measurements. Test results showed an average difference of 3 decibel milliwatts (dBm) for a tent type RA, 15 dBm for a metal RA and 14 dBm for a Built-in-Place RA for a frequency range of 150 to 3000 MHz. These results can be used in calculating the available link budget for a communication system to determine if a signal will reach the inside of the RA.
Resonance in Laminar Pipe Flow of Non-Linear Viscoelastic Fluids
Authors: Letelier Mario F. , Siginer Dennis A. , Almendra Diego L. , Stockle Juan S.
Published: January 2019

The relaxation response of viscoelastic fluids associated with the natural frequencies of oscillation that arise as a consequence of the structure of the constitutive equation is explored for the case of pulsating flow. The matching of the forcing frequency to the fluid’s natural frequencies induces a multiple resonance phenomenon.

In this paper, the resonance phenomenon is investigated in pulsating flow in straight circular tubes when the fluid is characterized by the Johnson-Segalman constitutive model. An analytical solution is developed based on an asymptotic expansion in terms of a material parameter. The analysis reveals that the forcing frequency associated with the pressure gradient can generate a sequence of resonances of decaying intensity dependent on the material parameter and other fluid constitutive constants. The effects of resonance on the rate of flow and oscillating velocity field are explored for several values of the relevant parameters.
Simulation of Nucleate Boiling With Interfacial Temperature Gradients and Sharp Interface
Authors: Perez-Raya Isaac , Kandlikar Satish G.
Published: January 2019

Effective heat transfer techniques benefit the development of nuclear and fossil fuel powered steam generators, high power electronic devices, and industrial refrigeration systems. Boiling dissipates large heat fluxes while keeping a low and a constant surface temperature. However, studies of the fluid behavior surrounding the bubble and the heat transfer near the contact-line are scare due to difficulties of flow visualization, chaotic conditions, and small length scales. The preset study shows the simulation of bubble growth over a heated surface from conception to departure. The computation of mass transfer with interfacial temperature gradients leads to proper bubble growth rates. Models to include the interface sharpness uncover the dynamic and thermal interaction between the interface and the fluid. Results indicate that the nucleation of a bubble (in water at 1 atm with 6.2 K wall superheat) has an influence region of 2Db (where Db is the departure bubble diameter). In addition, results reveal a thin thermal film near the interface that increases the heat transfer at the contact-line region. Numerical bubble growth rates compare well with experimental data on single bubble nucleation.
Application of a Resonant Metamaterial Line Array in Ultrasound Compressive Imaging
Authors: Ghanbarzadeh-Dagheyan Ashkan , Molaei Ali , Heredia-Juesas Juan , Martinez-Lorenzo Jose Angel
Published: January 2019

Acoustic metamaterials have been proposed for numerous applications including subwavelength imaging, impedance matching, and lensing. Yet, their application in compressive sensing and imaging has not been fully investigated. When metamaterials are used as resonators at certain frequencies, they can generate random radiation patterns in the transmitted and received waves to and from a target. Compressive sensing favors such randomness inasmuch as it can increase incoherence by decreasing the amount of mutual information between any two different measurements. This study aims at assessing whether the use of resonating metamaterial unit cells in a single-layered array between a number of ultrasound transceivers and targets can improve the sensing capacity, point-spread function of the sensing array (their beam focusing ability), and imaging performance in pointlike target detection. The theoretical results are promising and can open the way for more efficient metamaterial designs with the aim of enhancing ultrasound imaging with lower number of transceivers compared to the regular systems.
System Identification for Control of a Bow Thruster With Brushless Motor and Shaft-Less Propeller
Authors: Ramidi Priyatham Sanjeeva Reddy , Xiros Nikolaos I. , Lalizas Stavros , Papavasileiou Anastasios , Douvris Vasileios , Theodorou Nikolas , Lalizas Alexandros
Published: January 2019

In this work, a bow thruster is proposed to be used onboard small and medium-size watercraft, like motor yachts, fishing boats, patrol boats, ocean exploration vessels etc. with conventional or unconventional hull designs including displacement hull, planing hull, catamarans, SWATHs, SES, and so on. As oftentimes the case, a magnetic coupling is employed. Specifically, magnetic coupling is used to transfer torque from a brushless motor’s stator to its rotor through a magnetic field rather than a physical mechanical connection. Such magnetic coupling is very convenient for liquid pumps and as, in our case, propeller systems, since a static, physical barrier can be placed between the stationary and rotating part of the system to separate the fluid from the electrically supplied stator operating in air. Therefore, magnetic couplings preclude the use of shaft seals, which eventually wear out and fail from the sliding of two surfaces against each other. In this work, a system identification process of a rim driven bow thruster is implemented employing data series obtained by tests on a prototype scale model. System Identification leads to a black-box model of the system. The model derived can be extrapolated by grey-box modeling techniques for further design improvements. A control system for the proposed thruster is developed and validated through both computer and hardware-in-the-loop simulation, after its implementation onboard a broadly used industrial Programmable Logic Controller (PLC). The mathematical model of the bow thruster mechanism is developed and the performance is analysed by using Matlab/Simulink.
An Improved Analytical Model of Friction and Ball Motion in Linear Ball Bearings With Application to Ball-to-Ball Contact Prediction
Authors: Lin Bo , Duan Molong , Okwudire Chinedum E. , Wou Jason S.
Published: January 2019

The friction behavior of rolling ball machine components like linear ball bearings is very important to their functionality. For instance, differences in linear velocity of balls induces ball-to-ball contact in certain circumstances, resulting in significant increases and variations in friction. In this paper, an improved analytical formula for determining the linear velocity of balls in four-point-contact linear ball bearings is derived as a function of contact angle deviations and contact forces. The analytical formula is validated against a comprehensive friction model in the literature and shown to be in good agreement, while an oversimplified analytical model proposed by the authors in prior work is shown to be inaccurate. A case study is presented where insights gained from the derived analytical formula are used to mitigate velocity difference of balls in a linear ball bearing which otherwise would experience ball-to-ball contact.
Correlating Thermal Characteristics From Flow-Reactor Experiments With Primary Reference Fuel
Authors: Wong Jun-Chun , Chen Lea-Der
Published: January 2019

An experimental investigation was conducted to correlate thermal characteristics with primary reference fuel (PRF) using an “isothermal” flow reactor. Objective of the investigation was to assess whether or not thermal characteristics measured in a radiant-heated flow reactor could serve as an indicator of fuel octane number. The experimental set-up consisted of a radiant furnace and a pyrex-tube test section inside. The pyrex tube was fitted with thermocouples alongside the tube wall. Four PRF compositions of iso-octane and n-heptane were considered: 0, 65, 85 and 100% of iso-octane by volume; noted as PRF0, 65, 85 and 100, respectively. The test conditions reported in the paper set the fuel-air mixture temperature to 180 °C at the inlet of the test section and the radian furnace temperature to 345 °C. The equivalence ratio was set in the range 0.93 to 2.0. For a pre-set PRF and equivalence-ratio condition, the experiments were run with fixed mixture velocities over the range 0.019 m/s to 0.400 m/s. Over the conditions tested, the thermocouples recorded two temperature oscillations along the flow reactor for each of PRF0, 65 and 85 mixtures. Both oscillation locations moved downstream when PRF number was increased and the two oscillation locations merged when PRF was set to 85. No temperature oscillations were recorded for experiments with PRF100 mixture. The results suggest that the temperature oscillation locations from the experiments using isothermal flow-reactors can be used to correlate fuel octane number.
On the Proper Description of Complex Network Dynamics
Authors: Yang Chun-Lin , Suh C. Steve
Published: January 2019

Real-world networks are dynamical complex network systems. The dynamics of a network system is a coupling of the local dynamics with the global dynamics. The local dynamics is the time-varying behaviors of ensembles at the local level. The global dynamics is the collective behavior of the ensembles following specific laws at the global level. These laws include basic physical principles and constraints. Complex networks have inherent resilience that offsets disturbance and maintains the state of the system. However, when disturbance is potent enough, network dynamics can be perturbed to a level that ensembles no longer follow the constraint conditions. As a result, the collective behavior of a complex network diminishes and the network collapses. The characteristic of a complex network is the response of the system which is time-dependent. Therefore, complex networks need to account for time-dependency and obey physical laws and constraints. Statistical mechanics is viable for the study of multi-body dynamic systems having uncertain states such as complex network systems. Statistical entropy can be used to define the distribution of the states of ensembles. The difference between the states of ensembles define the interaction between them. This interaction is known as the collective behavior. In other words statistical entropy defines the dynamics of a complex network. Variation of entropy corresponds to the variation of network dynamics and vice versa. Therefore, entropy can serve as an indicator of network dynamics. A stable network is characterized by a specific entropy while a network on the verge of collapse is characterized by another. As the collective behavior of a complex network can be described by entropy, the correlation between the statistical entropy and network dynamics is investigated.
Direct Ink Writing of Graphene Oxide Reinforced PDMS Matrix Composites for Improved Mechanical Properties
Authors: Liu Chao , Jiang Li , Ding Junjun
Published: January 2019

Recently, PDMS has been widely used because of its outstanding properties, such as its biocompatibility, moldability, and Mechanical Flexibility. However, the low mechanical strength hinders its ability for further applications. The Addition of graphene oxide (GO) into Polydimethylsiloxane (PDMS) matrices as a reinforcement is a reasonably simple way to improve its mechanical properties. Direct ink writing (DIW) is an ideal method for printing viscous materials which provides useful advantages for fabrication, such as higher design freedom, as well as having no requirement for a castable mold, compared to conventional PDMS processing methods. Herein, we demonstrate the DIW 3D printing of GO reinforced PDMS matrix composites. PDMS SE 1700 and Sylgard 184 were mixed in 4:1 and 7:3 ratios as matrix materials with controlled rheological properties. GO, synthesized by modified Hummer’s method, was loaded into PDMS at various weight ratios (0.5%, 1%, 2%, 3% and 4%) to fabricate GO/PDMS composites. The GO dispersed uniformly throughout the PDMS matrix with no visible aggregation during the mixing and printing processes. Tensile tests were performed using 3D printed dog-bone shape GO/PDMS bars to evaluate the enhancement of the GO reinforcement. The results showed that the Young’s modulus of PDMS increased by 58.7% with 1% GO reinforcement.
Uncertainty Quantification of Edwards High-Pressure Pipe Behavior Using Complex System Thermal-Hydraulics Codes
Authors: Raheli Kaleibar Mojtaba , Pourgol-Mohammad Mohammad , Khoshbakhti Saray Rahim , Hoseyni Seyed Mohsen
Published: January 2019

There are different types of uncertainty sources in the Complex System Thermal-Hydraulics Codes calculations resulting in inaccurate computations. The sources include boundary and initial condition, model structure, their corresponding parameters, user inputs, the numerical techniques and the errors in the validation test data. Regarding the codes structure, the uncertainty sources are utilization of simplified mathematical models expressing conservation laws, thermodynamics laws, state equations applicability, discretization of governing equations, and physical characteristics of the simulated system. The Edwards high-pressure test tube is a well-known test for verifying the results of simulating complex numerical codes. On the other hand, the existence of deterministic values in the initial, boundary conditions and geometric dimensions can challenge the results of this experiment.

In this study, a probabilistic approach is utilized to study the behavior of the Edwards High-Pressure pipe using RELAP5 Complex System Thermal-Hydraulics Code. A probabilistic distribution is estimated with appropriate accuracy for the experiment uncertainties.

An efficient approach consisting of Wilks sampling method is implemented to quantify the uncertainty of experimental results.
Uncertainty Quantification of Artificial Neural Network Based Machine Learning Potentials
Authors: Li Yumeng , Xiao Weirong , Wang Pingfeng
Published: January 2019

Atomistic simulations play an important role in the material analysis and design by being rooted in the accurate first principles methods that free from empirical parameters and phenomenological models. However, successful applications of MD simulations largely depend on the availability of efficient and accurate force field potentials used for describing the interatomic interactions. As a powerful tool revolutionizing many areas in science and technology, machine learning techniques have gained growing attentions in the field of material science and engineering due to their potentials to accelerate the material discovery through their applications in surrogate model assisted material design. Despite tremendous advantages of employing machine learning techniques for the development of force field potentials as compared to conventional approaches, the uncertainty involved in the machine learning interpolated atomic potential energy surface has not drew much attention although it is an important issue. In this paper, the uncertainty quantification study is performed for the machine learning interpolated atomic potentials, and applied to the titanium dioxide (TiO2), an industrially relevant and well-studies material. The study results indicated that quantifying uncertainties is an indispensable task that must be performed along with the atomistic simulation process for a successful application of the machine learning based force field potentials.
Thermodynamic Modeling of Allam Cycle
Authors: Sifat Najmus S. , Haseli Yousef
Published: January 2019

Deterioration of environment caused by the release of harmful greenhouse gases (mainly CO2) from the power plants has become an area of growing concern. At the present, various methods are being investigated for capturing and storing CO2. Current technologies require a huge amount of energy leading to reduction in overall efficiency. The introduction of Allam cycle, which uses high pressurized super critical CO2 as working fluid has added a new dimension to solve this problem. This is an innovative oxy-fuel power cycle which ensures a near zero emission through inherent capture of all CO2. This paper concentrates on performance modeling of an Allam cycle. The effects of various input parameters are analyzed for achieving highest efficiency. Performance of each component in the cycle is investigated separately and combined therefore to get the overall performance of the cycle. The impact of using an ASU without intercooling and then supplying the high temperature outlet gases except oxygen to the recuperator is investigated. Although, a high power is consumed within ASU, the overall energy requirement decreases as extra energy becomes available in the recuperator to preheat the recycled CO2. An efficiency of 55% is predicted for the cycle.
A Virtual Sensor for Soot Load Estimation in Diesel Particulate Filters
Authors: Magar Pratik , Anwar Sohel , Izadian Afshin
Published: January 2019

In this paper, a new method for measuring the DPF soot load is proposed which does not require any physical sensors for its operation. This method is applicable for all the automobiles equipped with a turbocharger. The proposed virtual sensor utilizes the information on the turbocharger turbine speed variations to estimate the DPF soot load. Simulation results show that the proposed method offers an effective way to accurately estimate the soot load in DPF. The proposed method can have a significant impact on improving the DPF regeneration process efficiency (and thereby fuel efficiency) by eliminating the use of less reliable differential pressure sensor based DPF soot load estimation.
An Excel Add-in for Accreditation Data Collection and Auto Grading Sheets (AGS): A Canadian Experience
Authors: Ismail Mohamed
Published: January 2019

In this paper, an Excel Add-in or Xl-App for automating grade recording and graduate attributes assessment at the course level is presented. The Xl-App is one of the three major constituents of the OBACIS System. At the course level, the purpose of the Xl-App is twofold: 1) cutting down the grade compilation and accreditation reporting time and effort by an order of magnitude using the built-in OBACIS accreditation and grading sheets (AGS) module 2) introducing an advanced tool for data-driven continuous improvement (DCI) for enhancing the teaching and learning experience at both course and program levels. The app has a third module used to collect additional information related to accreditation reporting. This information is required by the course information sheets (CIS) mandated by CEAB accreditation questionnaire. The Win-app has a dedicated module that serves that purpose called OBACIS Catalogs. The Xl-App is capable of emitting the data collected in both XLSX and XML formats. The data collected can be easily exported to learning management systems (LMS), grade books, and web marking systems. The OBACIS Win-App can easily parse the data collected from different faculty members using the Xl-App in their raw excel format and integrate them together to generate unified program and faculty-level assessment reports that can be utilized in generating top-down continuous improvement action plans. The Xl-App has been in implementation since early 2015. It had remarkable impact on enhancing the teaching and learning experience of a handful of courses taught by the author. The App improved the robustness of course grading and saved a tremendous amount of time needed for grade and accreditation reporting.