bluuebunny/crossref_metadata_2025 huggingface dataset:
Effective Property Estimation of CMC Minicomposites Considering Porosity
Authors: Nagaraja Abhilash M. , Gururaja Suhasini
Published: January 2019

Ceramic matrix composites (CMCs) are a promising subclass of composite materials suitable for high temperature applications. CMCs exhibit multiple damage mechanisms such as matrix cracking, interphase debonding, fiber sliding, fiber pullout, delaminations etc. Additionally, process induced defects such as matrix porosity exists at multiple length scales and has a considerable influence on the mechanical and failure behavior of CMCs. In the current work, the effect of intra-tow porosity, which exist at the micro-scale, on the mechanical behavior of CMCs has been investigated by numerical homogenization.

Micro-scale response of 3 phase CMCs with intra tow pores has been obtained by finite element analysis based homogenization. Pores have been modeled as non-intersecting ellipsoids in a square unit cell representative of matrix material. The effective mechanical properties of porous matrix at the micro scale has been obtained from numerical homogenization, which are in good agreement with Mori-Tanaka mean field theory. The obtained matrix elastic properties have then been included in a three phase unit cell consisting of fiber, interphase and matrix representative of CMC microstructure. The effect of porosity volume fraction and aspect ratio on the effective elastic properties of the composite have been reported. Homogenization approach to model statistical distribution of pore size obtained from X-ray computed tomography of CMC minicomposite has been proposed.
Influence of Injection Angle on Pollutant Emissions and Combustion Temperature on a CFM56-3 Engine
Authors: Moreira Pedro , Brójo Francisco
Published: January 2019

Air traffic increases and growing concerns about the environment raised interests in the study of ways to reduce pollutants emissions. One reason for combustor and downstream components damage is non-uniform distribution of fuel due to dirtiness or injector damage, increasing NOx and CO emissions due to higher and lower temperature zones. Hot spots also reduce components live. Fuel injection angle change with injector life and combustion behaviors also change with this parameter. Present work report CFD simulations of combustion in the combustion chamber of a CMF56-3 gas turbine engine, to evaluate influence of injection angle on pollutant emissions and combustion temperature. Concerning engine power setup, International Civil Aviation Organization Landing and Take-Off cycle (100%, 85%, 30% and 7% engine power) were used. From the studied injection angles, lowest temperature is for 58° and that angle also produced the lowest NOx for power setups lower than 85%. 70° produced higher NOx emissions. For CO, 58° had higher emissions and 70° lower. CO2 reduces for lower injection angles, opposite to UHC. Lower angles had better results, having 3% reduction in NOx with a reduction of 10° of the injection angle. Temperature also reduces 4% with a 10° injection angle reduction.
Pool Boiling Heat Transfer Enhancement of Water by Gold Nanoparticles With an Electrophoretic Deposition Method
Authors: Cao Zhen , Pham Anh Duc , Wu Zan , Ruzgas Tautgirdas , Alber Cathrine , Sunden Bengt
Published: January 2019

Saturated pool boiling heat transfer of water is investigated experimentally on copper surfaces with nanoparticle coatings at atmospheric pressure. The coatings are generated by an electrophoretic deposition method (EPD). Three modified surfaces are prepared with gold nanoparticles of 0.20 mg, 0.25 mg and 0.30 mg, respectively. During the deposition, ethanol works as the solvent while the electrical potential and deposition time are controlled as 9.5 V and 30 min, respectively. The experimental results show that heat transfer coefficients (HTC) and critical heat fluxes (CHF) are enhanced on the modified surfaces. HTC increases with decreasing thickness of the coating, while CHF increases with increasing thickness of the coating. CHFs of EPD-0.20 mg, EPD-0.25 mg and EPD-0.30 mg are 93 W/cm2, 123 W/cm2 and 142 W/cm2, respectively, which are increased by 7%, 41% and 63% compared with the smooth surface. EPD-0.20 mg performs the best on heat transfer, with a maximum enhancement of around 60%. At the end, a brief review about mechanistic models of heat transfer at low and moderate heat fluxes is provided, based on which, the reasons why heat transfer is enhanced are discussed.
Compliance Effect on the Flow Condition in Vascular In Vitro Experiments
Authors: Matsuura Masami , Tupin Simon , Ohta Makoto
Published: January 2019

Endovascular treatment has become the standard for intracranial aneurysm management. In vitro systems including an artery model are required for devices evaluation and clinician training. Although silicone is usually use for such model, its compliance is known to be lower than blood vessels. The purpose of this study was to analyze the influence of model material compliance on flow properties.

Silicone and 12 [wt%] poly (vinyl alcohol) hydrogel (PVA-H) were used to create two box-shaped models of significantly different compliance. The inner lumen geometry was a 4 [mm] diameter straight tube (parent vessel) and a 10 [mm] diameter sphere representing the aneurysm. A blood-mimicking fluid made of a mixture of glycerin, water and sodium iodide was used to reproduce the viscosity and density of blood and fit models refractive index. The circulation system consisted of a pulsatile blood pump and resistance valve. A flow rate of 250±50 [ml/min] and pressure from 75 to 115 [mmHg] were set inside the model. Pressure and flow rate sensors were used to monitor flow conditions before and after the model. Particle image velocimetry (PIV) was performed to record the difference of flow patterns inside the aneurysm of both model using a Nd:YAG solid laser system and fluorescent particles.

Results revealed a significant change of flow conditions due to model compliance. Attenuation of the flow rate pulse was recorded between the inlet and the outlet of the both model. This attenuation was 51% for PVA-H model. Moreover, a time lag between outlet pressure and outlet flow rate curves was recorded in both model. This time lag was longer with the PVA-H model, as this model exhibit a greater compliance.

PIV experiments revealed significant changes of flow patterns and velocity inside the aneurysm. Because of its high compliance, PVA-H model walls moved under the pulsatile conditions. A change of flow direction and decrease of its velocity were observed near the proximal wall of the aneurysm, compared to the silicone model. Such differences might modify the stress on the wall of the aneurysm.

To conclude, our experiments revealed that compliance has significant impacts on flow properties and should be taken into account for in vitro vascular model manufacturing.
A New Wideband Microwave Antenna for Breast Cancer Detection
Authors: Wang Lulu , Xu Jinzhang
Published: January 2019

Previous studies have shown that microwave imaging offers an alternative or additional way for early diagnosis of breast cancer. Microwave antenna plays an important role in a microwave imaging system. The paper presents a wideband microwave antenna for medical microwave breast imaging application. Various simulations were conducted to validate the proposed antenna. Results show that the proposed antenna has the potential for application in a microwave imaging system to identify breast lesions.
CFD-Based Aerodynamic Analysis of the Flow Past an Airfoil With Passive Trapezoidal and Perforated Vortex Generators
Authors: Bou-Mosleh C. , Himo R. , Habchi C.
Published: January 2019

Passive vortex generators are widely used for heat and mass transfer enhancement in static mixers and heat exchangers. Trapezoidal vortex generators are used in the high efficiency vortex static mixer (HEV) because they generate a complex flow structure enhancing the transport phenomena. Moreover, vortex generators are used on airfoils and cars to delay or suppress flow separation. The flow past triangular and rectangular winglets was studied in the open literature showing good performance in enhancing the lift and drag coefficients. In the present study, a non-conventional vortex generator is proposed consisting on an inclined trapezoidal tab similar to that used in the HEV static mixer. In addition, the tab is perforated at its center (circular perforation). Inline array of several vortex generators are fixed on an airfoil and the drag and lift coefficients are analyzed for different geometries using computational fluid dynamics. Different cases are analyzed where the inclination angles of the vortex generators are changed and their effect is investigated. Furthermore, the effect of changing the size of the vortex generator is also assessed. The results are then compared to conventional vortex generators, mainly triangular winglets. The present results are validated against experimental and numerical data from the literature. The results show that the drag coefficient can be reduced with such vortex generators. They also show good agreement with experimental results for the lift coefficient.
Experimental Analysis of Alternative Dielectric Materials for DBD Plasma Actuators
Authors: Rodrigues F. F. , Pascoa J. C. , Trancossi M.
Published: January 2019

Dielectric Barrier Discharge plasma actuators are simple devices with great potential for active flow control applications. They have very interesting features which have made them a topic of interest for many researchers, for instance they present very low mass, fast response time, low cost, easy implementation and they are fully electronic with no moving parts. The dielectric material used in the construction of these devices present an important role in their performance. The variety of dielectrics studied in the literature is very restrict and the majority of the authors make use of Kapton, Teflon, Macor ceramic or PMMA. Furthermore, several authors reported difficulties in the durability of the dielectric layer when actuators operate at high levels of voltage and frequency. Considering this background, the present study focus on the experimental testing of alternative dielectric materials which can be used for DBD plasma actuators fabrication. Considering this, plasma actuators with dielectric layers made of Poly-Isobutylene rubber, Poly-Lactic acid and Acetoxy Silicon were experimentally tested. Although these dielectric materials are not commonly used in plasma actuators, their values of dielectric strength and dielectric permittivity indicate they can be good solutions. The plasma actuators facbricated with these alternative dielectric materials were experimentally analysed in terms of electrical characteristics and induced flow velocity, and the obtained results were compared with an actuator made of Kapton which is, currently, the most common dielectric material for plasma actuators. The effectiveness of the actuators was estimated and the advantages and disadvantages of the use of each dielectric material were discussed.
An Experimental Setup to Characterize Boundary Layer Asymmetry on a Spinning Projectile Using Magnetic Resonance Velocimetry
Authors: Siegel Noah W. , Schlenker Aaron P. , Sullivan Kevin D. , Valdez Isaiah L. , Snow Chase P. , Benson Michael J. , Van Poppel Bret P. , Elkins Christopher J. , Rodebaugh Gregory P.
Published: January 2019

Current CFD models fail to accurately predict boundary layer asymmetry on spin-stabilized projectiles, particularly in the transonic and subsonic flow regimes. Consequently, these models cannot accurately characterize the Magnus moment, a key component in aerodynamic behavior. This work seeks to capture boundary layer thickness asymmetry, an indicator of Magnus effects, around a spinning projectile using Magnetic Resonance Velocimetry (MRV). The MRV technique allows for collection of three-dimensional, non-intrusive, high-resolution velocity field measurements that can be used for comparison to and validation of current computational models. In this experiment, a modified M80 projectile was designed to thicken the hydrodynamic boundary layer for technique validation. The scaled projectile was mounted in a custom-designed test rig at a 2° nosedown angle of attack. The apparatus rotated the projectile at various spin rates in a constant flow of copper-sulfate solution. Initial results revealed azimuthal differences in boundary layer thickness for three different cases — no spin, nominal spin, and double spin — particularly in the tapered rear (boattail) region of the projectile. The introduction of spin shifted the boundary layer thickness in the spin direction resulting in lateral boundary layer asymmetry in the boattail region, a phenomenon that likely affects the stability of spin-stabilized projectiles.
Validation and Evaluation of Turbulence Models in Thermal Predictions of a Small Data Center Facility
Authors: Hu Beichao , Phan Long , Lin Cheng-Xian
Published: January 2019

Thermal management in data centers has become more and more important due to the rapid growth in power density in modern data centers. Computational fluid dynamics (CFD) is proved to be a very useful tool in data center design and analysis. However, the previous papers always utilize k-epsilon model, and has never studied on the effect of other turbulence models. This paper will demonstrate the difference between various turbulence models in terms of accuracy and computational time. The data center investigated in this paper has a floor area of 900 ft2 and comprises one rack, one CRAC unit, and several perforated tiles. This paper mainly investigates the effect of various turbulence models on CFD simulation in data center. The Turbulence model is believed to be a possible factor to improve the CFD results. The most suitable turbulence model will be identified based on a balance in both accuracy and computing resource requirements. Four turbulence models were investigated in this paper. The present investigation suggested that A&S 1-equation model yield the best accuracy and required the least computational time. Hence, 1-eqaution model should be the preferable turbulence model for CFD simulation in data center in the future.
Collaborative Multidisciplinary Engineering Design Experiences in IoT (Internet of Things) for Teachers Through Summer Research Site Program
Authors: Karbalaei Alireza , Turgut Damla , Dagley Melissa , Vasquez Eleazar , Cho Hyoung J.
Published: January 2019

The objective of the NSF RET (Research Experiences for Teachers) site program hosted by the University of Central Florida is to provide K-12 teachers with a hands-on engineering design experience covering all aspects of the Internet of Things, from the manufacturing of a sensor, to the hardware and software that allows it to connect to the Internet. This program gives teachers learning opportunities to explore the practical use of science for engineering applications, and provide a context in which students in their classroom can test their own scientific knowledge as they recognize the interplay among science, engineering and technology. The uniqueness of this site program lies in the engagement of teachers in various facets of scientific, engineering, and educational methods based on Train-the-Trainer model with rotation in multiple research labs. In order to support the STEM educational services for teachers and students in middle and high schools, our site program aims at creating competent teacher trainers who ensure quality pre-service and in-service teacher education, by providing multidisciplinary experiences that are relevant to the current technical development. Teachers in the adjacent public school districts are primary participants in this site program. Significant efforts have been made to recruit teachers serving underrepresented student populations, and female and minority teachers who can reach out to them.

In our RET site program, the participants rotated to four different laboratories with a 1.5–3 week residency in each, where they learned about the practice of engineering in various disciplines at the research laboratories on the university campus under the guidance of faculty and graduate mentors. The teachers presented their learning outcomes in the final week and were invited back to share their educational implementation experiences in their classes. This site program provided teachers with interdisciplinary engineering design experiences relevant to innovative technical development, and helped them develop teacher-driven teaching modules that can be deployed in the classroom.
Welding Robotic Co-Worker Using Brain Computer Interface
Authors: Li Yao , Kesavadas Thenkurussi
Published: January 2019

Robotic co-workers are an emerging generation of physical robots promises to transform manufacturing with its ability to communicate and collaborate, both robot-to-robot and robot-to-human, opening the way to greater innovation and productivity. We designed a welding robotic co-worker which observes industrial part, searches welding seams, plans welding trajectory, and simulates welding result automatically. It largely benefits small and medium-sized manufacturing enterprises (SMEs) by allowing manufacturers handle low-volume orders without re-programming. As a co-worker, the robot communicates with its operator though brain computer interface (BCI) as well as guarantees the operator’s safety. We demonstrated the performance of this robot using a human subject study in welding simulation environment.
Cooling Systems for Refuge Alternatives in Hot Mine Conditions
Authors: Yan Lincan , Yantek David , Reyes Miguel , Damiano Nicholas , Srednicki Justin , Bickson Joseph , Whisner Bruce , Bauer Eric
Published: January 2019

The accumulated heat and humidity inside occupied refuge alternatives (RAs) can impose risk of heat stress to the occupants. The accumulated heat could be from the metabolic and environmental sources. For hot mines, the high ambient temperature makes it more difficult to dissipate heat accumulated inside the RA. A cooling system is then needed to reduce the interior heat and humidity. Two types of cooling systems were tested out for their cooling capacity. One cooling system is a portable, battery-powered, air conditioning system and the other is a portable cryogenic air supply. During the testing, the mine air temperature surrounding the RA was elevated to and maintained at 85°F to simulate hot mine environment. The tests demonstrated that both cooling systems were able to control the air temperature inside the RA even though they did not last the entire duration of a 96-hour test. This paper provides an overview of the test methodology and findings as well as guidance on improving the performance of both cooling systems, including: optimizing the cooling cycle for the battery-powered AC system and increasing the flow rate and tank storage capacity for the cryogenic system. The information in this publication is useful for RA manufacturers and mines to develop the cooling systems that will enable providing the life sustaining environment in mines with elevated temperatures.
A Hyperbolicity Analysis of the 1991 OLGA’s Model for Isothermal Flow
Authors: Sondermann Carina N. , de Freitas Raphael V. N. , Patricio Rodrigo A. C. , Figueiredo Aline B. , Bodstein Gustavo C. R. , Rachid Felipe B. F. , M. Baptista Renan
Published: January 2019

Multiphase flows are encountered in many engineering problems. Particularly in the oil and gas industry, many applications involve the transportation of a mixture of oil and natural gas in long pipelines from offshore platforms to the continent. Numerical simulations of steady and unsteady flows in pipelines are usually based on one-dimensional models, such as the two-fluid model, the drift-flux model and the homogeneous equilibrium model. The 1991’s version of the well-known and widely-used commercial software OLGA describes a system of non-linear equations of the two-fluid-model type, with an extra equation for the presence of liquid droplets. It is well known that one-dimensional formulations may be physically inconsistent due to the loss of hyperbolicity. In these cases, the associated eigenvalues become complex numbers and the model loses physical meaning locally. This paper presents a numerical study of the 1991’s version of the software OLGA, for an isothermal flow of stratified pattern, in a horizontal pipeline. For each point of interest in the stratified-pattern flow map, the eigenvalues are numerically calculated in order to verify if the eigenvalues are real and also to assess their signs. The results indicate that the model is conditionally hyperbolic and loses hyperbolicity in a vast area of the stratified region under certain flow conditions. Even though the model is not unconditionally hyperbolic, some simulations here performed for typical offshore pipeline flows are shown to be in the hyperbolic region.
Electrokinetic Remediation of Contaminated Soils With Chromium
Authors: Ribeiro A. , Vilarinho C. , Araújo J. , Carvalho J.
Published: January 2019

Soil is a vital natural resource that regulates our environment sustainability and provide essential resources to humans and nature. Nowadays, with an increasingly populated and urbanized world, pollution is widely recognized as a significant challenge to soil and groundwater resources management. The most common chemicals found in soils and water plumb in a dissolved state and considered as potential pollutants are heavy metals, dyes, phenols, detergents, pesticides, polychlorinated biphenyls (PCBs), and others organic substances, such as organic matter. Unlike organic contaminants, heavy metals are not biodegradable and tend to accumulate in living organisms and many heavy metal ions are known to be toxic or carcinogenic. Toxic heavy metals of particular concern zinc, copper, nickel, mercury, cadmium, lead and chromium. Electrokinetic remediation deserves particular attention in soil treatment due to its peculiar advantages, including the capability of treating fine and low permeability materials, and achieving consolidation, dewatering and removal of salts and inorganic contaminants like heavy metals in a single stage.

In this study, the remediation of artificially chromium contaminated soil by electrokinetic process, coupled with Eggshell Inorganic Fraction Powder (EGGIF) permeable reactive barrier (PRB), was investigated. An electric field of 2 V cm−1 was applied and was used an EGGIF/soil ratio of 30 g kg−1 of contaminated soil for the preparation of the permeable reactive barrier (PRB) in each test.

Results proved that the study of chromium mobility revealed the predominance in its transportation through the soil towards the anode, due essentially to the existence of chromium in the form of oxyanions (chromate and dichromate), which confers a negative charge to the molecule. Chromium removal by electrokinetic remediation was faster in low levels of concentration and the utilization of citric acid as buffer and complexing agent allowed to maintain pH of soil below the precipitation limit for this element. It was obtained high removal rates of chromium in both experiments, especially near the anode. In the normalized distance to cathode of 0.8 it was achieved a maximum removal rate of chromium of 55, 59 and 60% in initial chromium concentration of 500 mg kg−1, 250 mg kg−1 and 100 mg kg−1, respectively.

The viability of the new coupling technology developed (electrokinetic with EGGIF permeable reactive barrier) to treat low-permeability polluted soils was demonstrated. Based on the proved efficiency, this remediation technique has to be optimized and applied to real soils in order to validate it as a large-scale solution.
Effect of Graphene on Mechanical Performance of Pin-Loaded Circular Hole in Laminated Composites
Authors: Aluko Olanrewaju
Published: January 2019

An analytical modeling was performed to investigate the effect of Nano filler on the mechanical performance of carbon fiber reinforced composite joints using the characteristic curve method. The joints were prepared from carbon fiber reinforced laminated plates with and without graphene nanoplatelet (GNP) and the characteristic dimensions used to determine the characteristic curve were evaluated from stress functions without experimental tests. The load-bearing capacity of the joints were carried out using different coefficient of friction and Yamada-Sun failure criterion along the characteristic curve. The evaluated results showed that the infusion of graphene nanoplatelet into the epoxy matrix of fiber reinforced composite plate increases the failure load of the composite joints.
Modelling and Design of an Airship Crane
Authors: Azouz Naoufel , Khamlia Mahmoud , Benabdallah Fida , Guesmi Fatma
Published: January 2019

This paper presents the design and the dynamic modeling of a Smart Crane called CHAYASC, designed to equip wide-body airship, which has to carry out loading and unloading operations from a certain altitude. The main function of this crane is to lift, stabilize, maneuver and position large loads by having precise control of the position and orientation of these loads according to the six degrees of freedom.

The CHAYASC is based in particular on a Cable Driven Parallel Manipulator and will have a dual mission: 1) deposit and arrange the containers in the hold of the airship, 2) lift and stabilize the containers suspended during a sudden movement of the airship under the effect of a gust of wind.
Large Deformation Analysis and Experiments With Double Parallelogram Compliant Mechanisms
Authors: Tanksale Abhijit A. , Gandhi Prasanna S.
Published: January 2019

Compliant mechanisms are highly preferred in applications demanding motion with high precision. These mechanisms provide friction-less, backlash-free precise motion obtained through deformation of flexible members. The double parallelogram compliant mechanism (DPCM) is one the most important compliant mechanisms to obtain highly precise straight-line motion. DPCM when operated in horizontal plane yield high precision straight-line motion (even with large deformations) useful in several engineering applications. However, constraints such as space, dead loads, etc. may demand DPCMs to be used in the vertical plane. For DPCMs operating in a vertical plane, the axial load due to gravity causes tension and compression in flexible beams which get coupled to bending under large deformations. This ultimately affects the parasitic error of straight-line motion. This paper presents a coupled analysis, along with experimental validation, of DPCM operating in vertical plane considering gravity effects with large deformation.
Cross Sectional Area Changes due to Plastic Bending of Prismatic Bars
Authors: Zielinski Michael J. , Cinoglu Ismail Soner
Published: January 2019

Given the current trend in manufacturing to decrease part variability, and in order to increase product quality, dimensional tolerances are becoming more exacting. With this in mind, and with the decreased time allotted for components to progress from design to manufacture, it has become more critical that accurate models of the manufacturing process are developed. This paper investigates the changes in cross sectional area when a prismatic bar is plastically deformed into a ring of constant diameter. Through further processing, these rings are transformed into components that function to secure mechanical components, such as bearings, into assemblies. Failure of the ring can cause significant damage, or failure of the assembly. Typical thickness tolerances are on the order of +/−.002” (0.05 mm), but can be as small as +/−.0002” (0.005 mm). Also, a growing trend in manufacturing is for the final ring to have a specified thickness on the inner and outer edge within this tolerance band. The rings are produced in various metallic materials with different mechanical properties by continuously coiling prismatic bars to a specific diameter. An analytic model based on small strain theory was developed for the simple cross sections of rectangular and trapezoidal geometries. This model was then extended to include the effect of a hyperbolic rather than linear stress distribution through this simple section in order to relieve the constraints of small strain theory and adequately model the actual process. An empirical model was developed based on experimental observations. A numerical model was developed using the commercial finite element analysis (FEA) software Abaqus (SIMULIA, Providence, RI) to simulate the manufacturing process. This was compared to the empirical model developed from production parts for validation. Once the finite element model is validated, it could be used to explore the effects of design parameters (initial dimensions of the prismatic bar, material properties etc.) and create efficient designs for manufacturing. The empirical model can then be used in the design process. Additionally, the numerical simulation could be used to model more complex cross sectional areas which cannot be evaluated analytically. There was adequate agreement between the empirical and numerical models to the extent that the numerical model could be used for more complex cross sectional geometries. A further refinement of the analytic model to include finite strain theory should be used to expand on this.
Measuring the Impact of a New Mechanical Engineering Sophomore Design Course on Students’ Systems Thinking Skills
Authors: Degen Cassandra M. , Muci-Küchler Karim H. , Bedillion Mark D. , Huang Shaobo , Ellingsen Marius
Published: January 2019

As the complexity of cutting edge products increases with advances in technology, there is a need to include activities in the undergraduate curriculum that allow students to learn basic systems engineering concepts, that promote the development of their systems thinking skills, and that allow them to practice these skills. To this end, the aim of this work was to impact students’ systems thinking skills at an early stage of their mechanical engineering curriculum, develop assessment tools to measure sophomore-level mechanical engineering students’ system thinking skills, and observe trends in measured systems thinking skills both before and after exposure to a new sophomore design course.

This paper provides an overview of the new course, gives details about an Engineering Systems Thinking Survey (ESTS) that was developed to assess systems thinking skills in specific areas, and presents the results of the ESTS from implementation of the course during two separate semesters. The specific areas that were targeted were identification of customer needs, setting target product specifications, concept generation, and systems architecture. The survey results showed that the course was successful in improving students’ self-efficacy on each of the four topics, particularly in setting target specifications and systems architecture. In addition, comparisons of pre- and post-ESTS results showed improvements in student answers on the technical questions related to identification of customer needs, setting target product specifications, and concept generation, with a slight decrease in the area of systems architecture.

While the newly developed course was successful in the dissemination of fundamental systems thinking and systems engineering concepts among students, the survey results indicated the need to strengthen students’ awareness of concept implementation. Future work will explore how to improve the course activities to help students learn how to apply the concepts, particularly for the topics of setting target specifications and systems architecture.
Ablation Characteristics of Nanosecond Laser Pulsed Ablation of Aluminum
Authors: Wang Yeqing , Diaz Daniel , Hahn David W.
Published: January 2019

This research presents laser ablation characteristics of an aluminum alloy after nanosecond pulsed laser ablation (PLA) with a 1064 nm Nd:YAG laser. White light interferometry and scanning electron microscopy were used to establish relationships between laser ablation characteristics and the number of pulses at different beam energies. Laser ablation features studied in this research are crater profiles, radii and depth, and extent of surface damage. An extensive damaged area around the laser ablation crater was found and is believed to be produced by the laser-induced plasma generated during PLA. Spectroscopic analysis showed that there is a correlation between the plasma formation threshold and the initiation of the plasma-affected area, and laser ablation at different angles of incidence between the beam and the sample showed a correlation between the plasma shape and the shape of the damaged area around the ablation crater. However, the variables influencing the occurrence of the plasma-affected and the extent of plasma-induced damage are not yet fully recognized and understood.
Development and Investigation of a Solar-Biogas Hybrid Brayton Cycle for 100 kW Power Generation
Authors: Alshahrani Saad , Engeda Abraham
Published: January 2019

The growth of demand for energy is increasing rapidly, and most current power generation is heavily dependent on fossil fuels. Using fossil fuels for power generation is not a secure future and is limited. The most abundant source of energy is solar energy. Concentrated solar power collectors have become one of the most effective choices to convert solar energy to heat, which can then be used to drive heat engines. Over the past decade, research on hybrid solar-gas turbines have shown good promise. This paper examines and studies the performance and design aspects of a hybrid micro solar-biogas turbine and its component technology for supplying low-carbon electricity on off-grid regions. Brayton cycle based several cycles are analyzed including a recuperator system. 100 kW unit system is designed.
Computational Modeling of Coagulopathy for Decision Support
Authors: Saltsman Brandon , Balaban Carey , Vipperman Jeffrey S.
Published: January 2019

Nearly everyone, throughout their life, is at risk of being involved in a serious traumatic event, such as motor vehicle accidents, sports and occupational injuries, or natural disaster related injuries. Twenty-eight percent of trauma patients precipitously develop abnormalities in their blood coagulation system. These coagulopathies increase their mortality rate by 5fold. The current coagulopathy diagnosis protocol collects basic patient information, vital signs, and performs traditional lab and point-of-care (POC) blood testing. A high-stakes decision must then be made by the trauma surgeon, using their intuition, training, and the results from the blood drawn at least 15 minutes prior, to determine the requirement for a resuscitation treatment through coagulation inhibitors or activators. Computational modeling and system analysis of the human blood coagulation are integral to developing superior decision support tools for trauma surgeons. In short, the coagulation system consists of the following functional subsystems: 1) blood flow, 2) platelet function, 3) diffusion, 4) advection, and 5) biochemical kinetics. We utilize a combined approach of both 0-D and 3-D model development with the overarching goal of developing a validated, near real-time decision support system. The biochemical kinetics of the coagulation system is implemented in the 0-D model with a set of 113 nonlinear, coupled ordinary differential equations (ODEs), describing the time rate of change of the numerous chemical concentrations and their interaction with one another. 0-D models provide a fast, efficient means of simulating the coagulation biochemical kinetics, but these ODEs lack the ability to describe the global effects of fluid flow, advection, and diffusion. Hence, the set of 113 ODEs are modeled as source terms and combined with the Navier-Stokes and chemical advection/diffusion equations in a three-dimensional finite volume computational domain, providing a global coagulation model. Model validation studies employ parallel experimental POC blood testing and 3-D computational modeling. Results from the 0-D model are consistent with testimonials from expert trauma surgeons, whom verify the model provides appropriate reasoning for their difficulties in predicting patient outcome. Thus, validated computational models have potential as a hypothesis generator used for developing new approaches for providing trauma surgeons with sufficient information to make better informed clinical decisions, “the decision support tool,” leading to decreased mortality.
Product Design in a Global Economy
Authors: Arnett Michael D. , Forero Rueda Manuel A. , Guenther Dennis A.
Published: January 2019

The emergence of a global economy has proposed new challenges for the product design engineer and provided new risks for the consumer. While the design and manufacturing processes have changed, the objective of providing a consumer product that is safe for public use still remains. This task becomes challenging for the product design engineer since the ability to oversee all aspects of the design, manufacture, and use is very limited and yet the mentality of “if you build it, you will be sued” is ever present. This paper considers three very different consumer products and all suffered a failure which resulted in harm done to the user. The first product is a multipurpose tool that, even though abuse was observed, contained a concealed danger as a result of poor design and/or manufacture that resulted in the injury. Second is a hanging chair that fell from the supporting fastener causing injury. Analysis and testing were unable to repeat the failure, thus severe abuse by the user proved to be the causal factor. Finally, a wine bottle opener caused injury as the user attempted to remove a part of the device from the packaging. In this case, the product itself was adequately designed to prevent injury for its intended use, but the packaging containing the product suffered from a faulty design. These cases exhibit different scenarios in which a consumer product caused injury to an end user and shows the varying entities that can bear the burden of negligence.
The Physics of Deep Surge in an Automotive Turbocharger Centrifugal Compression System
Authors: Dehner Rick , Selamet Ahmet
Published: January 2019

Deep surge is a violent fluid instability that occurs within turbomachinery compression systems and limits the low-flow operating range. It is characterized by large amplitude pressure and flow rate fluctuations, where the cross-sectional averaged flow direction alternates between forward and reverse. When a compressor transitions into deep surge, the time-averaged compressor outlet pressure and temperature decrease and increase, respectively, along with a drastic rise in narrowband, low-frequency noise.

The present study includes both measurements and predictions from a turbocharger centrifugal compressor installed on a gas stand. The compressor breathes air from ambient through an inlet duct with a bellmouth opening. The downstream compression system consists of a compressor outlet duct attached to a plenum with increased cross-sectional area, and an additional duct that connects the plenum outlet to a control valve. A detailed three-dimensional (3D) computational fluid dynamics (CFD) model of this compression system was constructed to carry out unsteady surge predictions. The results included here capture the transition from mild to deep surge, as the flow rate at the outlet boundary (valve) is reduced. During this transition, the amplitude of pressure and flow rate fluctuations greatly increase until they reach a repeating cyclic structure characteristic of deep surge. During the deep surge portion of the prediction, pressure fluctuations are compared with measurements at the corresponding compressor inlet and outlet transducer locations, where the amplitudes and frequency exhibit excellent agreement.

The predicted flow-field throughout the compression system is studied in detail during operation in deep surge, in order to characterize the unsteady and highly 3D structures present within the impeller, diffuser, and compressor inlet duct. Key observations include a core flow region near the center of the inlet duct, where the flow remains in the forward direction throughout the deep surge cycle. The dominant noise generation occurs at the fundamental surge frequency, which is near the Helmholtz resonance of the compression system, along with harmonics at integer multiples of this fundamental frequency.
A Numerical Study to Investigate the Influence of Edge Preparation in Vibration Assisted Machining
Authors: Pervaiz Salman , Kannan Sathish , Samad Wael Abdel
Published: January 2019

In machining operation, cutting tool performs a central role towards the overall machining performance. A user from metal cutting community always look for better cutting tools that can enhance productivity by reducing tool wear and cost. Modification in the micro-geometry of cutting edge is termed as edge preparation, and it is performed to improve the machining performance by strengthening the cutting edge, reducing internal stresses of coating and lowering the edge chipping etc. Edge preparation has a controlling influence on the formation of deformation zones, cutting temperature, cutting forces and stresses at the cutting interface. Vibration assisted machining (VAM) concept is gaining fame in the metal cutting sector community for machining difficult-to-machine materials. In VAM, cutting tool moves with a small amplitude vibration instead of moving with a constant cutting velocity. This small amplitude vibrational movement provides better machining performance for difficult-to-cut brittle materials. The current numerical study utilized different edge prepared micro-geometries such as sharp edge, round edge and chamfer edge etc. cutting tools, and then these cutting tools were used in the numerical simulations of VAM. The study shows higher magnitude of cutting forces under VAM with tools with modified geometry. The study is beneficial for the metal cutting community and opens new areas of industrial applications.
A Digital Twin Concept for Manufacturing Systems
Authors: Ellgass Wesley , Holt Nathan , Saldana-Lemus Hector , Richmond Julian , Vatankhah Barenji Ali , Gonzalez-Badillo Germánico
Published: January 2019

With the developments and applications of the advanced information technologies such as cloud computing, internet of thing, artificial intelligence and virtual reality, industry 4.0 and smart manufacturing era are coming. In this respect, one of the specific challenges is to achieve a connection of physical resources on the shop floor with virtual resources, for real-time response, real time process optimization, and simulation, which is merged by big data problem. In this respect, Digital Twins (DT) concept is introduced as a key technology, which includes physical resources, virtual resources, service system, and digital twin data. DT considers current condition of physical resource and prediction of future events to make a responsive decision. However, due to the complexity of building a digital equivalent in virtual space to its physical counterpart, very little applications have been developed with this purpose, especially in the industrial manufacturing area. Therefore, the types of data and technology required to build the DT for a manufacturing system are presented in this work, trying to develop a framework of DT based manufacturing system, which is supported by the virtual reality for virtualization of physical resources.
Thermal Behavior of Soils Under Tidal Effect: A Case Study in Guayaquil, Ecuador
Authors: Moreira Daniel , Macías José , Hidalgo-León Ruben , Soriano Guillermo
Published: January 2019

This research analyzes the tidal effect in the thermal properties of the ground for a case study in Guayaquil, Ecuador. A thermal response test (TRT) performed near the shore of the Guayas river presented periodic fluctuations in the thermal behavior concurrent with the tide cycle. First, an analytical solution for tide-induced water table fluctuations was used for the determination of the phreatic level for the days of the test. The analytical model accounted for the horizontal distance from the shore, the ground porosity, and permeability. Afterward, a geometric mean model was used to predict the thermal conductivity of soil considering the groundwater level fluctuations. Finally, a correlation between the effective thermal capacity of the ground and the phreatic level in the soil was found.
Finite Element Analysis of the Passenger Rail Equipment Workstation Table Sled Test
Authors: Eshraghi Shaun , Severson Kristine , Hynd David , Perlman A. Benjamin
Published: January 2019

Fixed workstation tables in passenger rail coaches can pose a potential injury hazard for passengers seated at them during an accident. Tables designed to absorb impact energy while minimizing contact forces can reduce the risk of serious injury, while helping to compartmentalize occupants during a train collision. The Rail Safety and Standards Board (RSSB) in the U.K. issued safety requirement GM/RT2100, Issue 5 [1] and the American Public Transportation Association (APTA) in the U.S. issued safety standard APTA PR-CS-S-018-13, Rev. 1 [2] with the goals of setting design and performance requirements for energy-absorbing workstation tables.

The U.S. Department of Transportation, Federal Railroad Administration (FRA) Office of Research, Development and Technology directed the Volpe National Transportation Systems Center (Volpe Center) to evaluate the performance of the Hybrid-III Rail Safety (H3-RS) anthropomorphic test device (ATD), also known as a test dummy, in the APTA sled test in order to incorporate a reference to the H3-RS in the safety standard. The Volpe Center contracted with the manufacturer of the H3-RS, Transport Research Laboratory (TRL), in the U.K. to conduct a series of sled tests [3] with energy-absorbing tables, donated by various table manufacturers. The tables were either already compliant with the RSSB table standard or were being developed to comply with the APTA table standard.

The sled test specified in Option A of the APTA table standard involves the use of two different 50th percentile male frontal impact ATDs. The H3-RS and the standard Hybrid-III (H3-50M) ATDs performed as expected. The H3-RS, which features bilateral deflection sensors in the chest and abdomen, was able to measure abdomen deflections while the H3-50M, which features a single sensor measuring chest compression, was not equipped to measure abdomen deflection.

This study attempts to validate a finite element (FE) model of the APTA 8G sled test with respect to the thorax response of the H3-RS and H3-50M. The model uses a simplified rigid body-spring representation of one of the energy absorbing tables tested by TRL. The FE models of the H3-RS ATD and the H3-50M ATD were provided by TRL and LSTC, respectively. Results from the sled tests and FE simulations are compared using data obtained from the chest accelerometer, the chest and abdomen deflection sensors, and the femur load cells. Using video analysis, the gross motion of the dummies and table are also compared. Technical challenges related to model validation of the 8G sled test are also discussed.

This study builds on previous analyses conducted to validate the abdomen response of the H3-RS FE model, which are presented in a companion paper [4].