bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear Oscillations of Particle-Reinforced Electro-Magneto-Viscoelastomer Actuators
Authors: Khurana Aman , Kumar Deepak , Sharma Atul Kumar , Joglekar M. M. 
Published: July 2021

Abstract
This work presents the dynamic modeling and analysis of a particle-reinforced and pre-stressed electro-magneto-viscoelastic plate actuator. The actuator belongs to a smart actuator category and is made of an electro-magneto-active polymer filled with a particular volume fraction of suitable fillers. An energy-based electro-magneto-viscoelastic model is developed to predict the actuator response and interrogate the impact of particle reinforcement on the dynamic oscillations of a pre-stressed condition of the actuator. An Euler–Lagrange equation of motion is implemented to deduce the governing dynamic equation of the actuator. The findings of the model solutions provide preliminary insights on the alteration of the nonlinear behavior of the actuator driven by DC and AC dynamic modes of actuation. It is observed that the enrichment in the particle reinforcement characterized by the amount of fillers strengthens the polymer and depleted the associated level of deformation. Also, the depletion in the intensity of oscillation and enhancement in the frequency of excitation is perceived with an increase in the particle reinforcement. In addition, the time-history response, Poincare plots, and phase diagrams are also plotted to assess the stability, periodicity, beating phenomenon, and resonant behavior of the actuator. In general, the current study provides initial steps toward the modern actuator designs for various futuristic applications in the engineering and medical field.
Anisotropic Cutting Force Characteristics in Milling of Maraging Steel Processed Through Selective Laser Melting
Authors: Tamura Shoichi , Matsumura Takashi , Ezura Atsushi , Mori Kazuo 
Published: July 2021

Abstract
Additive manufacturing (AM) process of maraging steel has been studied for high value parts in aerospace and automotive industries. The hybrid additive/subtractive manufacturing is effective to achieve tight tolerances and surface finishes. The additive process induces anisotropic mechanical properties of maraging steel, which depends on the laser scanning direction. Because anisotropy in the workpiece material has an influence on the cutting process, the surface finish and the dimension accuracy change according to the direction of the cutter feed with respect to the laser scanning direction. Therefore, the cutting parameters should be determined to control the cutting force considering material anisotropy. The paper discusses the cutting force in milling of maraging steel stacked with selective laser melting, as an AM process. Anisotropic effect on the cutting forces is proved with the changing rate of the cutting force in milling of the workpieces stacked by repeating laser scanning at 0/90 deg and 45/−45 deg. The cutting forces, then, are analyzed in the chip flow models with piling up of orthogonal cuttings. The force model associates anisotropy with the shear stress on the shear plane. The changes in the cutting forces with the feed direction are discussed in the cutting tests and analysis.
Anisotropic Material Behaviors of Three-Dimensional Printed Carbon-Fiber Polymer Composites With Open-Source Printers
Authors: Garcia Jordan , Harper Robert , Lu Y. Charles 
Published: July 2021

Abstract
Composite products are often created using traditional manufacturing methods such as compression or injection molding. Recently, additive manufacturing (three-dimensional (3D) printing) techniques have been used for fabricating composites. 3D printing is the process of producing three-dimensional parts through the successful combination of various layers of material. This layering effect in combination with exposure to ambient (or reduced) temperature and pressure causes the finished products to have inconsistent microstructures. The inconsistent microstructures along with the oriented reinforcing fibers create anisotropic parts with difficulty to predict mechanical properties. In this paper, the mechanical properties of fiber-reinforced polymer composites produced by additive manufacturing technique (3D printing) and by traditional manufacturing technique (compression molding) were investigated. Three open-source 3D printers, i.e., FlashForge Dreamer, Tevo Tornado, and Prusa i3 Mk3, were used to fabricate bending samples from carbon-fiber-reinforced acrylonitrile butadiene styrene (ABS). Results showed that there exist significant discrepancies and anisotropies in mechanical properties of 3D-printed composites. First, the properties vary greatly among parts made from different printers. Second, the mechanical responses of 3D-printed parts strongly depend upon the orientations of the filaments. Parts with the infill oriented along the length of the specimens showed the most favorable mechanical responses such as Young’s modulus, maximum strength, and toughness. Third, all 3D-printed parts exhibit inferior properties to those made by conventional manufacturing. Finally, theoretical modeling has been attempted to predict the mechanical responses of 3D-printed products and can potentially be used to “design” the 3D printing processes to achieve the optimal performance.
A Review on the Effect of Temporal Geometric Variations of the Coronary Arteries on the Wall Shear Stress and Pressure Drop
Authors: Freidoonimehr Navid , Chin Rey , Zander Anthony , Arjomandi Maziar 
Published: July 2021

AbstractTemporal variations of the coronary arteries during a cardiac cycle are defined as the superposition of the changes in the position, curvature, and torsion of the coronary artery axis markers and the variations in the lumen cross-sectional shape due to the distensible wall motion induced by the pulse pressure and contraction of the myocardium in a cardiac cycle. This review discusses whether modeling of the temporal variations of the coronary arteries is needed for the investigation of hemodynamics specifically in time-critical applications such as a clinical environment. The numerical modelings in the literature that model or disregard the temporal variations of the coronary arteries on the hemodynamic parameters are discussed. The results in the literature show that neglecting the effects of temporal geometric variations is expected to result in about 5% deviation of the time-averaged pressure drop and wall shear stress values and also about 20% deviation of the temporal variations of hemodynamic parameters, such as time-dependent wall shear stress and oscillatory shear index. This review study can be considered as a guide for future studies to outline the conditions in which temporal variations of the coronary arteries can be neglected while providing a reliable estimation of hemodynamic parameters.
Three-Dimensional Finite Element Modeling of Blast Wave Transmission From the External Ear to a Spiral Cochlea
Authors: Brown Marcus A. , Bradshaw John J. , Gan Rong Z. 
Published: July 2021

Abstract
Blast-induced injuries affect the health of veterans, in which the auditory system is often damaged, and blast-induced auditory damage to the cochlea is difficult to quantify. A recent study modeled blast overpressure (BOP) transmission throughout the ear utilizing a straight, two-chambered cochlea, but the spiral cochlea’s response to blast exposure has yet to be investigated. In this study, we utilized a human ear finite element (FE) model with a spiraled, two-chambered cochlea to simulate the response of the anatomical structural cochlea to BOP exposure. The FE model included an ear canal, middle ear, and two and half turns of two-chambered cochlea and simulated a BOP from the ear canal entrance to the spiral cochlea in a transient analysis utilizing fluid–structure interfaces. The model’s middle ear was validated with experimental pressure measurements from the outer and middle ear of human temporal bones. The results showed high stapes footplate (SFP) displacements up to 28.5 μm resulting in high intracochlear pressures and basilar membrane (BM) displacements up to 43.2 μm from a BOP input of 30.7 kPa. The cochlea’s spiral shape caused asymmetric pressure distributions as high as 4 kPa across the cochlea’s width and higher BM transverse motion than that observed in a similar straight cochlea model. The developed spiral cochlea model provides an advancement from the straight cochlea model to increase the understanding of cochlear mechanics during blast and progresses toward a model able to predict potential hearing loss after blast.
On the Hierarchy of Models for Pipe Transients: From Quasi-Two-Dimensional Water Hammer Models to Full Three-Dimensional Computational Fluid Dynamics Models
Authors: Martin N. M. C. , Wahba E. M. 
Published: July 2021

Abstract
A hierarchy of models exists in the literature for the simulation of pipe transients. One-dimensional (1D) water hammer models provide a cost-effective tool for the analysis of such transients. Traditional 1D models implement a quasi-steady approximation of the frictional term, which results in poor modeling of the attenuation of the transient. To improve the modeling of the attenuation phenomenon, alternative unsteady friction models were developed for the 1D water hammer formulation. Moreover, quasi-two-dimensional (quasi-2D) water hammer models were introduced, which allow the computation of the unsteady velocity profile and hence provide improved modeling of the attenuation phenomenon. Recently, interest has developed in the use of computational fluid dynamics (CFD) models based on the Navier–Stokes equations in the simulation of fluid transients. Both axisymmetric and full three-dimensional (3D) CFD models are used in this regard. The aim of the current paper is to carry out a comparative study between the performance of quasi-2D water hammer models, axisymmetric CFD models, and full 3D CFD models. Numerical computations using the three models are performed for both laminar and turbulent flow cases. Present results show that the quasi-2D water hammer model and the axisymmetric CFD model provide near identical results in terms of computing the magnitude, phase, and attenuation of the transient. Reported results also demonstrate the computational efficiency of the quasi-2D model, which provides results that agree reasonably well with the full 3D CFD model results while using a grid density, which is an order of magnitude lower than the grid requirements for the full 3D CFD model.
Investigation on Optimal EES Capacity to Maximize Self-Consumption of PV System With Existing Energy-Efficient Houses in Korea
Authors: Lee Ru-Da , Lee Hyo-Mun , Kim Dong-Su , Yoon Jong-Ho 
Published: July 2021

Abstract
Battery systems are one of key factors in the effective use of renewable energy systems because self-production of electricity by renewables for self-consumption has become profitable for building applications. This study investigates the appropriate capacity of the Battery Energy Storage System (BESS) installed in all electric zero energy power houses (AEZEPHs). The AEZEPH used for this study is a high energy-efficient house, and its criteria indicates that all the electricity energy within the house is covered based on the generated electricity from on-site renewable energy systems, including that the annual net site energy use is almost equal than zero. The AEZEPHs used for this study is located in Daejeon, South Korea, and the experiment for measured data of electricity consumed and generated in the buildings is carried out for a year (i.e., Jan. through Dec. 2014). Based on the measured data, patterns of the electricity consumed by the AEZEPH and generated by an on-site renewable energy system (i.e., photovoltaic (PV) system), and the appropriate capacity of BESS is then analyzed and evaluated using the EES analysis tool, named Poly-sun. Results from this study indicate that the self-consumption can be increased up to 66% when the ESS system is installed and used during operated hours of the PV system, and the amount of received electricity during the week tends to be reduced by about two times.
Experimental Study on a Passive Solar Desalination Unit Associated With Fresnel Lens and Thermal Storage
Authors: Tan Jun-Yan , Ding Jun Wei , Ho Zhi Yong , Bahar Rubina 
Published: July 2021

Abstract
Passive solar stills can be a viable source of freshwater in water and energy scarce regions. However, the low production rate is one of the major drawbacks of passive solar stills. This work presents an experimental study of the combined effects of concentrated solar power (CSP) and phase change material (PCM) on a low-cost double slope passive solar desalination unit. Fresnel lens as the refractive CSP was used to converge the available solar irradiation onto the solar still basin that contained saline water. Metal tubes containing petroleum jelly with a melting point of 37°C were immersed as the PCM in the saline water. Four different experimental setups were tested in the natural tropical weather of Malaysia to identify the individual and combined impact of the lens and petroleum jelly on desalination performance. It was observed that the performance was better with the individual application of the CSP rather than the combination of CSP and PCM. There was a 28.21 % improvement in distillate production using Fresnel lens only; while using the Fresnel lens and PCM in combination showed a 25.64 % improvement in production. This study also provides several recommendations with which the experimental setup can be improved to yield better results in the future.
Effect of Altitude on In-Cylinder Heat Transfer of a Heavy Duty Diesel Engine
Authors: Liu Zhentao , Liu Jinlong 
Published: July 2021

Abstract
Diesel engines are the predominant power source in trucking industry. Heavy duty trucks move more than 70% of all goods transported around the United States. The atmospheric conditions vary with altitude but are vital to diesel engine performance, efficiency, and emissions. Existing studies reported reduced thermal efficiency and increased emissions when truck engines were operated at high altitude. As the heat loss is a key parameter related to engine efficiency, the goal of this paper was to investigate the altitude impacts on in-cylinder heat transfer characteristics. A single cylinder four-stroke heavy duty diesel engine was performed at constant speed and load but different intake pressure to simulate the varying atmospheric conditions at different altitude. The engine raised the amount of diesel mass injected to the cylinder per cycle to maintain the identical power output under decreased atmospheric pressure and to compensate the combustion deterioration happened inside the cylinder. The experimental results indicated a higher bulk temperature at high altitude due to a smaller amount of mixture mass trapped inside the cylinder. Such a larger temperature difference between the hot products and the cold walls increased in-cylinder heat transfer to the coolant, especially during the combustion period. Specifically, a rise in 2000m altitude resulted in up to ∼2% increment in heat loss to the atmosphere per fired cycle. As a result, applying thermal coating to improve fuel economy is more necessary in high altitude states, such as Colorado and Wyoming.
A Passive Ventilation and Air Conditioning System for an Office Space In Hot Climate
Authors: Harrouz Jean Paul , Ghali Kamel , Ghaddar Nesreen 
Published: July 2021

Abstract
Office spaces are characterized by strict constraints of thermal comfort and indoor air quality (IAQ) levels crucial for the occupants’ wellbeing and decision-making abilities. For these reasons, office spaces have large cooling loads especially in hot climates. Conventional vapor compression air conditioning systems are known to be energy intensive systems that rely mainly on electrical energy. Thus, there is a pressing need to decrease the reliance on active cooling systems by the introduction of passive cooling strategies and efficient sustainable buildings. This study proposes an effective passive cooling system that integrates a cross-flow dew point indirect evaporative cooler (DP-IEC) supplying cool clean air to an office space. Validated mathematical models were used to assess the integrated system’s ability in maintaining acceptable thermal comfort and IAQ levels at minimal energy and water consumption. The simulations were carried out for the peak load month for a case study of an occupied office located in the semi-arid and hot Lebanese inland region. The proposed system was able to meet the space thermal and IAQ constraints (average indoor temperature of 25.6 °C, CO2 concentration below 600 ppm). The optimized system operation yielded a daily energy and water consumption of 0.65 kWh and 52 L with a reduction of 80 % in the running cost as compared to the conventional mechanical system.
Lightweight PEM Fuel Cell Stack for Unmanned Aerial Vehicle
Authors: Jo Jinmyun , Zhang Xiaoyu , Ansari Ali 
Published: July 2021

Abstract
Fuel cell is an electrochemical device that converts fuel into electricity. Polymer electrolyte membrane fuel cells (PEMFCs) have been used for ground transportation due to its high efficiency and zero carbon emission. When it comes to unmanned aerial vehicles (UAVs), PEMFCs can support much longer flight endurance than internal combustion engines and batteries do. However, a lightweight PEMFC stack is required in order to carry enough payload for UAVs. In this research, a lightweight fuel cell stack was developed and fabricated based on the Horizon fuel cell stack. The stack components, including end plates, bipolar plates, and interconnects were redesigned and fabricated to replace those heavy components. Additive manufacturing (3D printing) and electroplating were used to fabricate bipolar plates and interconnects, whereas the end plates were machined from Garolite XX plates. The fabricated lightweight PEMFC stacks were tested using a Scribner 850e Fuel Cell Test System. The lightweight stack assembled with six electroplated bipolar plates showed that the maximum power density estimated was 3.514 W/cm2 with 4.5 V and 1.6 A/cm2 conditions for 100 ml/min of H2. The same fuel cell stack tested at 200 ml/min and 300 ml/min showed higher maximum power densities than 100 ml/min. The presentation includes design and fabrication, performance characterization, weight reduction strategy, and future work.
Computational Fluid Dynamics Based Investigation of the Performance of Hybrid Heat Sinks
Authors: Alkhazaleh Anas , Younes El-Saghir Selim Mohamed , Alnaimat Fadi , Mathew Bobby 
Published: July 2021

Abstract
This article discusses the mathematical modeling of a straight microchannel heat sink, embedded with pin-fins, for purposes of liquid cooling of microelectronic chips. The influence of three different geometrical parameters, pin fins’ diameter, pitch, and hydraulic diameter, on the heat sinks performance is studied. The studies are performed for Reynolds numbers varying from 250 to 2000, and the results are quantified based on thermal resistance and pressure drop. The heat sinks embedded with pin fins have better performance in terms of thermal resistance but at the same time have higher pressure drop. Studies revealed that increasing the pin fins’ diameter, pitch, and hydraulic diameter have an influence on the thermal resistance; the thermal resistance is found to be decreasing with increasing these parameters for the same Reynolds number. For the cases studied, the reduction in thermal resistance of straight microchannels embedded with pin fins varied from 18% to 60% compared with that of traditional straight microchannels for different heat sinks configurations and Reynolds number. On the other hand, the pressure drop is increasing with an increase in pin fins’ diameter and pitch, while it is found to be decreasing with increasing the hydraulic diameter.
A Numerical Investigation Into the Heat Transfer Performance and Particle Dynamics of a Compressible, Highly Mass Loaded, High Reynolds Number, Particle Laden Flow
Authors: Hassan Kyle , Kunz Robert , Hanson David , Manahan Michael 
Published: July 2021

Abstract
In this work, we study the heat transfer performance and particle dynamics of a highly mass loaded, compressible, particle-laden flow in a horizontally-oriented pipe using an Eulerian-Eulerian (two-fluid) computational model. An attendant experimental configuration [1] provides the basis for the study. Specifically, a 17 bar co-flow of nitrogen gas and copper powder are modeled with inlet Reynolds numbers of 3 × 104, 4.5 × 104, and 6 × 104 and mass loadings of 0, 0.5, and 1.0. Eight binned particle sizes were modeled to represent the known powder properties. Significant settling of all particle groups are observed leading to asymmetric temperature distributions. Wall and core flow temperature distributions are observed to agree well with measurements. In high Reynolds number cases, the predictions of the multiphase computational model were satisfactorily aligned with the experimental results. Low Reynolds number model predictions were not as consistent with the experimental measurements.
Determining Parametric Effects for Droplet Evaporation on Nanoporous Superhydrophillic Surfaces Using Machine Learning Techniques
Authors: McClure Emma R. , Carey Van P. 
Published: July 2021

Abstract
Experimental results demonstrate that droplet vaporization on metal surfaces can be significantly enhanced with the application of a nanoporous, superhydrophilic surface coating. A thin layer of ZnO nanopillars can be easily seeded and grown on most metallic surfaces to achieve nanoscale pores between pillars, and ultra-low apparent contact angles. These surface coatings have the potential to improve spray cooling processes, and can be easily scaled up to larger and more complex heat exchangers. In order to characterize the potential improvement to a spray cooling system it is important to understand the dependence on system parameters, and to have a clear model of droplet vaporization on such surfaces. There are a number of surface and impact parameters that will affect the droplet spreading and subsequent vaporization on the surface. The surface contact angle, wicking speed and impact velocity all interact to affect the maximum spread of the droplet and the speed at which the droplet reaches this state. Along with variations in droplet volume and wall superheat, the model for droplet vaporization becomes more complex and nonlinear. Instead of exploring a single parameter at a time, machine learning tools can be utilized to determine the dependence of droplet evaporation time on these parameters simultaneously. In this study a genetic algorithm and a neural network were used to develop a droplet evaporation model for these superhydrophilic surfaces. Each algorithm demonstrated clear advantages depending on whether speed, accuracy, or an explicit mathematical model was prioritized.