bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational Fluid Dynamics Validation of the Upper Respiratory System
Authors: Taherian Shahab , Rahai Hamid , Bonifacio Jeremy , Lopez Samuel , Lee Yong , Jafari Behrouz , Waddington Thomas 
Published: January 2018

Verification of numerical results with experimental data is an important aspect of any in silico study. In the case of the upper respiratory system, the air flow is often turbulent, which highlights the importance of validating an accurate turbulence model for numerical simulations. Patient specific CT based upper airway models were used for computational fluid dynamics (CFD) analyses of the upper respiratory system and the results were compared with the corresponding experimental results. Detailed CFD simulations were conducted using the STAR-CCM+ software to investigate the most appropriate numerical approach in accurately predicting flow characteristics in the upper respiratory system. Large Eddy Simulations (LES) and Reynolds-Averaged Navier-Stokes (RANS) equations with k-ε, and k-ω turbulence models were investigated.
The experiments include simulating inspiratory-expiratory flow with particle injection at the intake. A stereolithographic (SL) system (3-D system Projet 6000HD), with a resolution of 0.001–0.002 inches per inch of part and VisiJet SL Clear material, was used for fabricating the experimental model. The outlet of the model was connected to a manifold, with subsequent connection to a piston-cylinder system where a computer-controlled motor was used to simulate the normal breathing flow conditions. Investigations of flow characteristics within the upper airway were performed with a 2-D µPIV system from Intelligent Laser Applications (ILA for micro particle image velocimetry) which includes a high power green LED light source with an effective area of 100×100 mm, and a pulsing system (LPS controller). Matlab software was used for the post processing of PIV images.
The LES results displayed more detailed transient flow characteristics than the RANS results for both turbulence models. At the early time steps, the numerical results of the average velocity from all three methods were nearly identical. However, further downstream, where obstructions and strong velocity gradients exist, results differ with a larger velocity gradient near the wall for the LES simulation. Comparing the numerical and experimental results, due to seeding limitations, the experimental results did not display detailed low speed flow characteristics and thus, the shear stress and turbulence quantities were less than the corresponding CFD results. Further experiments are currently in progress to improve the experimental results and to better assess the transient numerical and experimental results.
Carbon Footprint of Energy Systems: Liquefied Petroleum Gas Based Cooking vs Electricity Based Cooking in Ecuador
Authors: Ramirez Angel D. , Perez Edgar F. , Boero Andrea J. , Salas Daniel A. 
Published: January 2018

Cooking is one of the most important final household uses of energy. In Ecuador, the main energy carrier for this use is liquefied petroleum gas (LPG), which normally is supplied in bottles. LPG is imported and heavily subsidized for household consumption. The Government has promoted the use of electric induction stoves provided the hydropower generation capacity in Ecuador is projected to grow.
Sustainability issues should be considered when changes in energy systems are analyzed. Life cycle assessment (LCA) is a methodological framework that can be used to quantify the environmental performance of any product or service, including energy systems. LCA can be used to quantify a range of environmental impact categories including Climate Change. The life cycle greenhouse gas emissions of a product or service are also known as carbon footprint.
The objective of this study is to quantify the change in the carbon footprint of the household cooking system from the current based on LPG to the proposed based on electricity, and the cumulative energy demand (CED) for cooking with both technologies, using the LCA methodology, in order to provide a basis for the development of policies to reach the maximum mitigation of greenhouse gases (GHG). Several scenarios that consider different electricity generation mixes, cooking efficiency and emissions profile are studied. The functional unit for comparison was defined as “1 effective MJ”, which is 1 MJ transferred to the food during cooking. System boundaries for the assessment included resources extraction, processing, energy carrier supply, cooking and manufacturing of the stove.
The results depend highly on the carbon footprint of the electricity system and, in a lesser extent, on the stove efficiency. Main results indicate that a carbon footprint mitigation occurs when changing the conventional LPG to a highly hydropower based cooking system, and that a higher life cycle energy efficiency is obtained when a high stove efficiency is considered. However, a greater carbon footprint may occur when cooking is performed using fossil derived power, which is a possible case when cooking is performed during peak demand of electricity.
Wear Performance of New Textured Surfaces Created by Modulation Machining
Authors: Tock Andrew , Gandhi Rahul , Saldana Christopher , Iglesias Patricia 
Published: January 2018

Methods for scalable surface texturing continues to receive significant attention due to the importance of micro-textured surfaces toward improving friction, wear and lubrication ability of mechanical devices. Controlled textures on surfaces act as fluid reservoirs and receptacles for debris and wear particles, reducing friction and wear of mating components. There are numerous fabrication techniques that can be used to create micro-sized depressions on surfaces, but each has limitations in terms of control and scalability. In the present study, modulation-assisted machining (MAM) is demonstrated as a viable approach to produce such textures, offering a potentially cost-effective approach for scalable production of these features on component surfaces.
In this work, the wear behavior of several textured surfaces created by MAM was studied using a ball-on-flat reciprocating tribometer. Textured and untextured alloy 360 brass disks were mated with stainless steel AISI 440C balls under lubricated conditions and variable sliding distance. The textured surfaces exhibited noticeably reduced wear under the longer sliding distances and the tribological performance of the surfaces depended on the size of the micro-dimples. Wear mechanisms are elucidated from the optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) observations and the implications for using such surfaces in practice are briefly discussed.
A Novel Platform-System to Study the Effects of a Vestibular Prosthesis on Non-Human Primate Postural Control
Authors: Thompson Lara A. , Haburcakova Csilla , Lewis Richard F. 
Published: January 2018

For the several millions of vestibular loss sufferers nationwide, daily-living is severely affected in that common everyday tasks, such as getting out of bed at night, maintaining balance on a moving bus, or walking on an uneven surface, may cause loss of stability leading to falls and injury. Aside from loss of balance, blurred vision and vertigo (perceived spinning sensation) are also extremely debilitating in vestibular impaired individuals. For the investigation of implants and prostheses that are being developed towards implementation in humans, non-human primates are a key component.
The purpose of our study was to implement a distinctive balance platform-system to investigate postural responses for moderate to severe vestibular loss and invasive vestibular prosthesis-assisted non-human primates (rhesus monkeys) for test balance conditions of various task-difficulty levels. Although the need for vestibular rehabilitative solutions is apparent, postural responses for a broad range of peripheral vestibular function, and for various stationary and moving support conditions, have not been systematically investigated.
The measurement system used in this research was unique in that it allowed us to conduct animal experiments, not investigated previously; such experiments are necessary towards the development on an invasive vestibular prosthesis to be used in humans suffering from vestibular loss. Our platform-system facilitated the study of rhesus monkey posture for stationary support surface conditions (i.e., quiet stance and head turns; more versus fewer footplate cues and large versus small base-of-support) and for dynamic support surface conditions (i.e., pseudorandom roll-tilts of the support surface). Further, the platform-system was used to systematically study postural responses that will serve as baseline measures for future vestibular-focused human and non-human primate posture studies.
Investigating Female Athletes’ Balance Using Center-of-Pressure (COP) Derived Displacement and Velocity Parameters
Authors: Badache Mehdi , Behera Lonika , Zhang Nian , Thompson Lara A. 
Published: January 2018

A realization of how specific exercises relate to balance performance is important for a wide demographic of individuals. Maintaining active and healthy living is particularly important for balance-impaired individuals (e.g., otherwise healthy individuals recovering from injury, fall-prone elderly, and stroke survivors) whom are interested in improving their balance for function in daily life. However, balance performance is also important for persons that are unimpaired (e.g., athletes). How balance performance may be improved as a result of, and in relation to, various athletic activities and exercises is a common question. Further, how certain activities can be used to prevent injury is an ultimate goal. Our objective was to compare standing balance in 3 unimpaired groups (i.e., female track & female tennis collegiate athletes and female non-athletes).
To assess static balance, participants performed stance variations increasing in difficulty-level, utilizing a wide or tandem stance (increasing or decreasing support base) and eyes-open or eyes-closed (limiting or providing visual cues), while standing on a forceplate walkway. Through the recorded ground reaction forceplate-based, center-of-pressure (COP) position time series, we extracted velocity and displacement parameters that aided in identifying differences between the above groups.
Our general findings were that anterior-posterior (AP, or front-to-back) COP displacement and velocity measures for female track athletes were unchanged relative to the (baseline) female non-athletes. However, mediolateral (ML, or side-to-side) measures, which have previously been shown to be associated with fall-risk, showed observable differences in displacement and velocity parameters, particularly for the female track athletes. Specifically, the female track athletes were better able to control their ML COP velocity in eyes-closed, wide, and eyes-open tandem conditions compared to non-athletes. However, tennis athletes had difficulty balancing in situations where eyes were closed (vision eliminated) and feet were tandem (base-of-support decreased) which was made apparent by the increases in all AP and ML COP-derived parameters. We interpreted this finding as the female tennis athletes were trained to rely heavily on visual cues (e.g., hand-eye or eye-body coordination), and also their balance may be more focused on maintaining their center-of-mass stability and body orientation, as opposed to COP per se.
Our study lends new insights as to how various types of athletic activities, and reliance on vision in athletes, impacts balance performance in un-impaired females.
The Emerging Render Alternatives: A Case Study Comparing the Utility and Aesthetics of the Printed and the 360 in Head-Mounted Display Formats for Architects and Non-Architects
Authors: Higuera-Trujillo Juan Luis , Rojas Juan-Carlos , Pistoni Pérez Mario , Iñarra Abad Susana 
Published: January 2018

Environmental simulations are fundamental part of the architecture and design language. Different systems have been incorporated as technology has progressed. Renders, widely used in Architecture, also presents this development. Although the traditional printed presentation has not changed in recent years, new methods such as the 360-Render displayed on Head-Mounted Displays (HMD) have recently emerged. However, currently there are few systematic comparisons between them. Hence, the objective of this preliminary work was to quantitatively compare these systems support for design: printed Render, and 360-Render in HMD.
Bipolar subjective scales were used as measurement method. Concepts were involved in utility, credibility, understanding of the space and dimensions, and basic aesthetics-emotional aspects. Survey was directed to two profiles: architects and non-architects. The analysis reveals significant results regarding these concepts, formats, and profiles. Results allow reflection on the new means of representation, both in professional and pedagogical scopes.
Thermo-Mechanical Response of Hybrid Polymer Composites During Tensile Loading
Authors: Prakash Raghu V. , Maharana Monalisha 
Published: January 2018

The fiber reinforced polymers are candidate materials for critical applications in view of the high strength, stiffness characteristics; however, they are highly anisotropic and have complex failure mechanisms. Thermo-mechanical response characterization is one of the means of identifying damage progression in these materials.
In this study, tensile tests were conducted on the hybrid composite laminates and Infrared thermographs were used to capture the thermal response of the specimen for the entire range of loading till failure. The tests were conducted on natural fiber composite specimens and hybrid (natural + synthetic fiber) composite specimens. The natural fibers used were in the form of uni-directionally stitched mats of Sunhemp, Kenaf and Flax fiber. The synthetic fibers used were bi-directionally woven Carbon fiber mat and Glass fiber mat. All the laminates were prepared using the hand lay-up technique. Four different configurations of the laminates were prepared. The natural fiber composite laminate comprised of Sunhemp fiber mat in a polyester resin system. The Sunhemp fiber mat was also used with woven Glass fiber mat on one side to prepare an unsymmetrical hybrid laminate. The Kenaf fiber mat was placed between layers of woven Glass fiber mats whereas the flax fiber mat was placed between the woven carbon fiber mats; Epoxy LY 556 and hardener Araldite® was used as the matrix. The finished laminate thickness was 2.1 mm and dog-bone tensile specimens were extracted using a CNC router. Some of the specimens were impacted at low velocities from two different heights to study the change in thermo-mechanical response, post-impact, during tensile test. Temperature response as a function of applied stress, failure strain and work done suggests that there is a correlation between the fracture events that take place during tensile test with the temperature response. In cases where there was a ply-drop failure, the rate of temperature change could identify the failure events, even though the resultant peak temperature was less. When the specimen failed by a single mode of failure (delamination/fiber failure), the temperature rise was found to be proportional to the input work done during tensile testing.
Nonlinear Vibrations of Woven Dacron Aortic Prostheses Conveying Pulsatile Flow
Authors: Tubaldi Eleonora , Amabili Marco , Païdoussis Michael P. 
Published: January 2018

Woven Dacron grafts represent standard implants for replacements of the thoracic aorta in current medical practice. Wide knowledge about the distinctly different mechanical properties of the Dacron implants with respect to the native aorta is available in literature while very little is known about the dynamic behavior of these prostheses.
This study addresses the dynamic response to pulsatile physiological blood flow and pressure of woven Dacron grafts currently used in thoracic aortic replacements. The structural model assumes a cylindrical orthotropic shell described by means of the nonlinear Novozhilov shell theory. Residual stresses because of pulsatile physiological pressurization are evaluated and included in the model. The pulsatile flowing fluid is formulated using a hybrid model that contains the unsteady effects obtained from linear potential flow theory and the viscous effects obtained from the unsteady time-averaged Navier–Stokes equations. Physiological waveforms of blood pressure and velocity are approximated with the first eight harmonics of the corresponding Fourier series. Coupled fluid-structure Lagrange equations for a non-material volume with wave propagation in case of pulsatile flow are utilized.
Frequency-response curves in the physiological range show the geometrically nonlinear vibration response to pulsatile flow with several superharmonic resonance peaks in the high physiological frequency range. Different values of modal damping are considered; in the limit case of low modal damping values, flow-induced asymmetric vibration of the aortic prosthesis is possible.
Finally, in order to reproduce the weave design of the woven Dacron fabrics, geometric imperfections are introduced in the structural model. The numerical natural frequencies of the pressurized prosthesis are compared with the experimental results obtained from the modal analysis of a woven Dacron graft.
Effects on Balance When Interfering With Proprioception at the Knee
Authors: Lahiff Christina-Anne , Schlafly Millicent , Reed Kyle 
Published: January 2018

After experiencing a stroke, 80% of individuals face hemiparesis causing muscle weaknesses, paralysis, and lack of proprioception. This often induces difficulty to perform everyday functions such as balancing. The goal of this project is to determine if stroke-like balance can be induced in healthy individuals. The Proprioceptive Interference Apparatus (PIA) applies vibrations and transcutaneous electrical nerve stimulation (TENS) about the knee joint in different combinations both with and without visual feedback.
Ten subjects stood on one foot for periods of two minutes for each of the eight trial conditions. The root mean squared (RMS) of the position coordinates, the standard deviation of the forces, and the RMS of center of pressure coordinates were analyzed for each trial and subject. Analysis of the variation of position markers and forces showed a statistically significant difference between balance with visual feedback versus without. However, the use of PIA did not have any statistically significant difference on these measures.
Ground Effect on Wings for Formula Student Race Cars
Authors: Epple Philipp , Hellmuth Manuel , Gast Stefan 
Published: January 2018

Aerodynamic design is getting continuously more important for formula student race cars. One very important aerodynamic device of these cars is the front wing. The front wings, as well as the rear wings generate a downforce to improve the stability of the vehicle especially when driving on curves. The front wings are mounted so close to the ground that they are already in ground effect. The rear wings are already too far from the ground and therefore are not in ground effect. Therefore it is very important to design the front wings in such a way as to maximise the ground effect. Therefore these wings have to be mounted at a proper distance from the ground in order to have the maximum ground effect. If the front wings are too close to the ground the ground effect disappears or even the downforce is less than far from the ground. Since the rear wings are out of the ground effect they have not been considered in this investigation.
In this work a series of wing designs, with different aspect ratios, at different angles of attack and at different distances from the ground where designed and investigated with computational fluid dynamics using the commercial Navier-Stokes solver STAR CCM+. The downforce lift coefficients of these wings in free flight as well as in ground effect and as the corresponding drag coefficients are presented. The best configurations of aspect ratio and angle of attack as well as the optimum distances from the ground to operate these front wings in ground effect are shown and the results discussed in detail.
Operational Energy Comparison of Concrete and Foamed Geopolymer Based Housing Envelopes
Authors: Villalba José Luís , Macías José , Baykara Haci , Ulloa Nestor , Soriano Guillermo 
Published: January 2018

The present article provides an operational energy comparison of modern concrete and foamed geopolymers as envelope materials for single unit housing in Ecuador. The study is performed by replacing the concrete material used in the walls and roof elements with foamed geopolymer components. Residential building sector requires around 35.6% of the total energy demand in Ecuador. For this reason, efforts on building practices improvement are relevant for the Ecuadorian society. The foamed geopolymers are a mixture of aluminosilicate material obtained from Ecuadorian natural zeolite, group of alkaline activators and the foamed agent that when mixing the raw materials and obtain the geopolymer.
To assess the potential use of foamed geopolymers as construction material, the annual energy demand for a social interest dwelling was obtained through simulation with EnergyPlus. Prefabricated Insulated Concrete Forms was established as the construction practice for the building model. Annual energy simulations were performed considering two Ecuadorian representative weathers, to Guayaquil and Quito locations.
Material properties of foamed geopolymers ware acquired by own experimental facilities. Thermal conductivity was obtained with the use of the hot plate method, while specific heat by means of differential scanning calorimetry (DSC) analysis. This analysis uses foamed geopolymers obtained from two procedures. Thus, these proposed materials presented low density, low thermal conductivity, and acceptable compressive strength values.
Finally, an assessment of natural geopolymers as a concrete replacement is presented, including a thermal characterization, and a sustainable construction evaluation. The findings affirm the key role of material selection in construction practices. Reductions around 4.0% in annual electricity demand was achieved for Guayaquil case, while energy consumption decreases around 1.3% for Quito.