bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Interlaminar Shear Damage Analysis of Fiber Reinforced Composites Improved by ZnO Nanowires
Authors: Marashizadeh Parisa , Abshirini Mohammad , Saha Mrinal , Liu Yingtao
Published: February 2021

In this study, the damage analysis of hybrid carbon fiber reinforced polymer (CFRP) composited with vertically aligned zinc oxide (ZnO) nanowires is investigated numerically. The effect of growing nanowires on improving the interlaminar shear strength (ILSS) of the hybrid structures is explored. The multi-scale model developed to make a bridge between the materials with different length scales available in the hybrid structures, including micro-scale, meso-scale, and macros-scale. The vertically aligned ZnO nanowires on the lamina and embedded in the epoxy matrix creates an enhancement layer. The effective material properties of this layer are evaluated at micro-scale by homogenization analysis. The cohesive zone method is employed in the meso-scale to explore the interfacial behavior and delamination (interlaminar damage) between the homogenized stacking layer and the CFRP lamina. Besides, the strain-based failure criterion is implemented at the macro-scale to investigate the progressive damage of fiber and matrix in CFRP plies. This analysis is programmed in user-defined subroutine linked to ABAQUS finite element software. The three-dimensional hybrid composite short beam in the three-point bending load is simulated in ABAQUS Explicit packager, and the ILSS is obtained. The damage behavior of hybrid composite is compared to the bare CFRP beam. The results indicate that aligning nanowires on the plies improves the performance of CFRP composites.
Evaluation of the Mechanical Properties of Repaired Composite Panels Using Resin Re-Infusion Process
Authors: Abd El-Latief Mahmoud E. , Shazly Mostafa , Bahei-El-Din Yehia
Published: February 2021

Glass Fiber Reinforced Plastics (GFRP) have been used in many fields such as aerospace, automotive and wind energy sectors. During their manufacturing processes, some defects such as dry spots and air pockets may develop in impregnated fabric, especially, when metallic inserts are used. To evaluate the interface between parent and repaired parts, an experimental study is performed to investigate its effect on the mechanical properties and structural integrity. To compare the response of the re-infused and intact samples, several tensile and bending tests were performed for uniaxial glass reinforcing fabric with tailored orientation for the interface between the intact and repaired regions. The results showed that for the tensile tests, repaired specimens with interfaces having 90° and 45° orientations w.r.t. loading direction were able to recover 80% and 73%, respectively, from the tensile strength of samples produced by vacuum infusion technique. However, for bending tests, the flexural strength was recovered by almost 90% and 72% for both interfaces, respectively. Based on visual inspection, each type of tested specimen has a typical dominant failure mode. For re-infused samples, the properties of the parent and repaired laminates determine the failure location.
Transient Performance of Heat Pipes Using Nanofluids
Authors: Mahdavi Mahboobe , Faghri Amir
Published: February 2021

In the present works, a comprehensive transient numerical model was developed to evaluate the effect of nanofluid on the transient performance of heat pipes. The numerical model solves for compressible vapor flow, the liquid flow in the wick region, and the energy equations in the vapor, wick and wall. The distinctive feature of the model is that it can uniquely determine the heat pipe operating pressure based on the physical and operating conditions of the system. Three nanoparticle types were considered: Al2O3, CuO, and TiO2. The effects of the concentration of nanoparticles (5%, 10%, 20% and 40%) were investigated on the heat pipe response time, thermal resistance, and pressure drop under various operating conditions. The results showed that the use of nanofluid decreased the response time of the heat pipe by the maximum of 27%. It was also discovered that the thermal resistance decreased significantly with an increase in the volume concentration. A maximum reduction of 84%, 82% and 78% in thermal resistance was obtained for Al2O3, CuO, and TiO2, respectively. In addition, the effect of nanoparticles on the liquid pressure drop highly depends on the nanoparticle type and volume concentration.
Optimization of Nodule and Height Sizes for Mixed Hydrophilic and Hydrophobic Surfaces
Authors: Frymyer Brian , Oztekin Alparslan
Published: February 2021

Patterned surfaces of hydrophobic and hydrophilic materials are considered to sustain dropwise condensation, providing the benefits of both materials and creating a surface with a low energy barrier for nucleation and capable of sustaining dropwise condensation. Surface heights, nodule sizes, and flow rates are evaluated on square-patterned surfaces to maximize mass collection. A thermal model is used to assess surface performance and includes an equivalent thermal resistance for diffusion. Flow rates of 15, 25, 50, and 100 m/s with nodule sizes between 0.1 mm to 3.6 mm are evaluated. Surface heights of 0.25, 0.5, 1, and 2 m are also assessed. For flow rates greater than 50 m/s, turbulent flow optimum nodule size is between 0.2 mm and 0.6 mm. Surfaces greater than 1 m in height at flow rates less than 50 m/s maximize mass with nodule sizes of 1.4 mm and 2 mm.
The Mechanism of Movement and Calculation of Blood Balance in the Flow Channel From the Left Atrium to the End of the Aorta
Authors: Talygin E. , Kiknadze G. , Gorodkov A.
Published: February 2021

Today, there are a lot of works studying the mechanisms of formation and evolution of self-organizing tornado-like jets of viscous fluid. In these works, the exact solution of the Navier-Stokes equation for such a class of flows are obtained, the geometry of the generating surface for that flows is established and the necessary and sufficient conditions for the formation and evolution of such swirling jets are formulated. However, important aspects of the mechanics of such flows remain unclear — the structure of the boundary layer, the shape of streamlines in general form, the structure of such flows under a pulsating flow regime, and others.

After obtaining the exact solution, attempts were made to obtain relations for streamlines in the corresponding projections. However, due to computational complexity, streamlines were constructed only for regions far from the axis of the swirling flow evolution. In this work, an alternative method of calculating streamlines was used, which made it possible to obtain general relations for these lines at each point in space. Expressions for streamlines contain easily computed functions, which simplifies their practical use Based on the expressions for streamlines, expressions were formulated declaring the conservation of the mass of the swirling blood flow from the left atrium to the aorta and the balance of the medium was calculated.

The results of this work are of great theoretical and practical importance. On the one hand, the established expressions for streamlines allow a better study of the mechanisms of formation and evolution of swirling flows in the axial region. On the other hand, obtaining quantitative ratios for the balance of blood in the heart and aorta allows a more accurate study of the mechanics of blood circulation.
A Computational Fluid Dynamics Analysis of Turbulence and Wakes of Horizontal Axis Wind Turbines During Non-Operational Time Periods
Authors: Al-Qarishey Hussein , Fletcher Robert W.
Published: February 2021

Wind turbines can create turbulence and downstream wakes which can introduce generation losses of downstream impacted turbines. These downstream turbine-induced losses are due to two different conditions. The first is from power-producing rotating blades of upstream wind turbines agitating the subsequent downstream wind in a cork-screw like manner. The second is from non-rotating, non-operational, non-power-generating wind turbines. These non-operating turbines may be under scheduled service shutdown, or rendered non-functional due to longer-term or permanent mechanical problems.

In this work CFD was used to study downstream turbulence and wakes of a utility-scale, non-operational three-blade horizontal axis wind turbines (HAWT). A flow field was constructed using an unstructured grid around a HAWT (rotor hub elevation of 80 meters and a blade length of 40 meters). Various wind velocities were studied up to 25 meters per second. Incompressible flow was used to assess downstream turbulence using a three-dimensional steady state and unsteady state SST k-ω (two equation) turbulence model. Different blade positions with respect to angle of attack (α) were studied, with a 4 degree angle of attack reported here. Pressures and velocities for distances of 100 meters in front and 500 meters downstream from the wind turbine are reported.
The Effect of Plate Curvature on the Influence of Macroscale Geometric Voids in Controlling Stress Wave Propagation
Authors: Florio C. S.
Published: February 2021

Much work has been done to create and understand means to control the propagation of acoustic and light waves through materials and structures. The ability to perform similar studies on the control of stress waves has implications not only for the development of capabilities to disrupt stress waves in order to limit their damage, but also to direct stress waves in order to tailor the behavior of a structure for a specific functional goal. Recent studies have demonstrated the use of voids and inclusions of varying size, geometry, arrangement, and composition in structures to attenuate impact forces or cloak stress waves in thin, flat, plane stress plates. However, many structures that may benefit from these wave modification methods are comprised of cylindrical shells. It is not currently known how well the techniques to control wave propagation and trends identified in plane stress plates can be applied to structures with cylindrical shells. Therefore, this study develops and uses computational modeling methods to examine the modification and control of stress waves induced by an axial impact load in metal plates of varying curvature through the inclusion of macroscale voids.

Methods are developed and used in this work to study the response of metal plates of varying curvature with and without voids of different shapes and arrangement to axial impact loads. The response is quantified through the magnitude of the fixed end reaction force and through normal oscillations of discrete points along the length of the plate. Fast Fourier transformation and wavelet coherence techniques are used to understand both the time-averaged and time-dependent oscillation behavior. Correlations are drawn between plate curvature and void design on the control of the propagation of stress waves. The knowledge gained can help guide the understanding design of these stress wave modification features.
Effect of Wire Electrode Materials on Performance Characteristics for Wire Electrical Discharge Machining of Metal Matrix Composite Material
Authors: Ramu Gurupavan Hurugalavadi , Ravindra Holalu Venkatadas , Muddegowda Devegowda Tadagavadi
Published: February 2021

Composite materials are the advanced materials which are widely used in manufacturing industries. The most commonly used composite materials are metal matrix composites. Due to the presence of abrasive reinforcing particles, traditional machining of these causes severe tool wear and hence reduces the life of cutting tool. Wire electrical discharge machining (WEDM) is quite successful for machining of metal matrix composites. Wire Electrical Discharge machining is a specialized thermal machining process capable of accurately machining parts of hard materials with complex shapes. One of the main research fields in WEDM is related to the improvement of the process productivity by avoiding wire breakage. Wire electrodes used in WEDM are the core of the system. In this study the effect of different wire electrode materials on electrode wear and surface finish for wire electrical discharge machining of metal matrix composite material were investigated. The experiments were conducted under the following process parameters viz., pulse-on time, pulse-off time, wire feed speed and current. For the experiment the aluminium 6061 alloy with 0%, 5%, and 10% of silicon carbide (SiC) reinforcement material was used. To conduct the experiment CNC wire EDM machine with two different wires viz., molybdenum and brass wire was used. Experimental results indicate that for better surface finish of Al6061 alloy, the brass wire is more suitable. The use of brass wire as electrode material leads to significant reduction in electrode wear in machining of Al-5%SiC and Al-10%SiC composite materials compare to molybdenum wire. Increasing percentage of silicon carbide in aluminium 6061 alloy increases the variation in surface finish and electrode wear. Wire wear rate of both brass and molybdenum wire is increased with increase in percentage of silicon carbide.
Influence of Random Variable Dimension on the Fast Numerical Integration Method of Aero Engine Rotor Disk Failure Risk Analysis
Authors: Junbo Liu , Shuiting Ding , Guo Li
Published: February 2021

In the risk assessment of turbine rotor disks, the probability of failure of a certain disk type (after N flight cycles) is a vital criterion for estimating whether the disk is safe to use. Monte Carlo simulation (MCS) is often used to calculate the failure probability but is costly because it requires a large sample size. The numerical integration (NI) algorithm has been proven more efficient than MCS in conditions entailing three random variables. However, the previous studies on the NI method have not dealt with the influence of random variable dimension on calculation efficiency. Hence, this study aims to summarize the influence of variable dimensions on the time cost of a fastintegration algorithm. The time cost increases exponentially with the number of variables in the NI method. This conclusion provides a reference for the selection of probability algorithms involving multiple variables. The findings are expected to be of interest to the practice of efficient security design that considers multivariable conditions.
Separation of Non-Viable Chinese Hamster Ovary (CHO) Cells Using Dielectrophoresis in a Deterministic Lateral Displacement Ratchet
Authors: Khan Mohammed , Chen Xiaolin , Xu Jie
Published: February 2021

Chinese hamster ovary (CHO) cell is the most widely used mammalian cell line for commercial production of therapeutic protein. Any presence of non-viable cells in culture medium may adversely affect subsequent functionality of these proteins. Therefore, separation of non-viable cells from suspending medium is critical in biopharmaceutical and biomedical sectors. One such method termed Deterministic Lateral Displacement has already shown promising capabilities in separating cells based on the cell size difference by taking advantage of the predictable flow laminae. However, in cases where size overlaps between viable and non-viable cells are present, separation based solely on size suffers and high-resolution separation techniques are required. Dielectrophoresis, one of the most widely used nonlinear electro-kinetic mechanism, has the potential to manipulate the same size cells depending on the dielectric properties of individual cells. In this work, we demonstrated that a DLD device can be combined with a frequency-based AC electric field to perform high resolution continuous separation of non-viable CHO cells from the viable or productive cells. The behavior of the coupled DLD-DEP device is further investigated by employing numerical simulation to check the effect of geometrical parameters of the DLD arrays, velocities of the flow field and required applied voltages. A moderate row shift fraction with velocity 700μm/s provided a good separation behavior without any trapping. The cell viability was also ensured by maintaining proper electric field which otherwise may cause cell loss due to ion leakage. Our developed numerical model and presented results lay the groundwork for design and fabrication of high resolution DLD-DEP microchips for enhanced separation of viable and nonviable cells.
Design of Yaw and Tilt Alignment Inspection System for a Low-Resolution 3D LiDAR Using Planar Target
Authors: Oh Seontaek , Yu Ji-Hwan , Eskandarian Azim , Kim Young-Keun
Published: February 2021

It is crucial to attach a LiDAR (Light Detection and Ranging), a 3D sensor for a mobile platform such as robot and vehicle within the acceptable misalignment to detect the relative positions of surrounding obstacles accurately. This paper proposes a novel inspection method to estimate the yaw and tilt alignment of a LiDAR after the sensor attachment. The proposed method uses a planar target board to estimate the yaw and tilt angles of a low-resolution LiDAR with milli-degree precision. Experiments were conducted to evaluate the accuracy and precision of the proposed method with the designed test-bench that can control the reference pointing angle of the LiDAR from −10 to 10 degrees. The experiment results on Velodyne VLP-16, a low-resolution LiDAR with 16 channels, showed that the proposed system estimated the yaw and tilt angles within accuracy and precision of 0.1 degrees.
Fluidic Injection Thrust Reverser System for High Bypass Ratio Turbofan Engines: Experimental Model
Authors: Kumar Raghav , Rajput Pankaj , Kumar Sunil
Published: February 2021

Conventional thrust reversers involve the usage of mechanical blockers which are bulky as they are designed to sustain heavy loads. As a result, they account for 30% of the nacelle weight (excluding the engine core). This added engine weight results in a 0.5%–1% increase in the specific fuel consumption of the aircraft. This paper advances our investigation of “Blockerless Engine Thrust Reversers” and uses it as an inspiration to optimize the system by designing an injection module (depicting an injection as a bleed from the core flow), conducting a computational analysis and demonstrating the viability of the process by building an experimental model of a 1:40 scale of a GE90 - 115B engine. A 3D printed experimental model was built after conducting an extensive parametric analysis. This model is used to demonstrate the viability of the “Fluidic Injection Thrust Reverser” (FITR) qualitatively and quantitatively.
A New Approach to Evaluate and Optimize Swirl Tube Demister Efficiency
Authors: Anderson Kyle , Reinhardt Ben , Sultani Walead , O' Hern Hannah , Zhang Xiang , Abbasi Bahman
Published: February 2021

The focus of this report is on a new technique to quantify the air-water separation efficiency of a swirl tube demister that has application in numerous water purification systems. This experimental study adds to the existing literature by quantifying the effect of design parameters on both the previously studied water collection efficiency, as well as the air bypass efficiency, defined as the ratio of the air mass flowrate exiting at the desired air outlet, over the inlet air mass flowrate. This parameter is important for the water purification field because air acts as a carrier of contaminants, necessitating that it does not leak into the purified water collection chamber. Results from this study showed there was a clear trend when comparing the air bypass efficiency to the inlet air to water ratio. As the inlet air to water ratio increased, the air bypass efficiency decreased. This trend was consistent among four different experimental apparatuses indicating that either the geometry of the swirl tube had very little effect of the air bypass efficiency, or that the ranges tested for dimensions thought to affect the swirl tube performance were not varied enough.
Periodic Motions in an Autonomous System With a Discontinuous Vector Field
Authors: Guo Siyu , Luo Albert C. J.
Published: February 2021

In this paper, periodic motions in an autonomous system with a discontinuous vector field are discussed. The periodic motions are obtained by constructing a set of algebraic equations based on motion mapping structures. The stability of periodic motions is investigated through eigenvalue analysis. The grazing bifurcations are presented by varying the spring stiffness. Once the grazing bifurcation occurs, periodic motions switches from the old motion to a new one. Numerical simulations are conducted for motion illustrations. The parameter study helps one understand autonomous discontinuous dynamical systems.
An Investigation of the Aerodynamic and Vibration Behavior of a Helicopter Rotor Blade
Authors: Pulok Mohammad Khairul Habib , Chakravarty Uttam K.
Published: February 2021

Rotary-wing aircrafts are the best-suited option in many cases for its vertical take-off and landing capacity, especially in any congested area, where a fixed-wing aircraft cannot perform. Rotor aerodynamic loading is the major reason behind helicopter vibration, therefore, determining the aerodynamic loadings are important. Coupling among aerodynamics and structural dynamics is involved in rotor blade design where the unsteady aerodynamic analysis is also imperative. In this study, a Bo 105 helicopter rotor blade is considered for computational aerodynamic analysis. A fluid-structure interaction model of the rotor blade with surrounding air is considered where the finite element model of the blade is coupled with the computational fluid dynamics model of the surrounding air. Aerodynamic coefficients, velocity profiles, and pressure profiles are analyzed from the fluid-structure interaction model. The resonance frequencies and mode shapes are also obtained by the computational method. A small-scale model of the rotor blade is manufactured, and experimental analysis of similar contemplation is conducted for the validation of the numerical results. Wind tunnel and vibration testing arrangements are used for the experimental validation of the aerodynamic and vibration characteristics by the small-scale rotor blade. The computational results show that the aerodynamic properties of the rotor blade vary with the change of angle of attack and natural frequency changes with mode number.
Vibration Suppression of an Elastically Supported Beam With Closely Spaced Natural Frequencies
Authors: Liu Haizhou , Gao Hao
Published: February 2021

Vibration suppression of distributed parameter systems is of great interest and has a wide range of applications. The dynamic performance of a primary system can be improved by adding dynamic vibration absorbers (DVA). Although the relevant topics have been studied for decades, the trade-off between capability of suppressing multiple resonant peaks and complexity of absorbers has not been well addressed. In this paper, the vibration suppression problem of a uniform Euler-Bernoulli beam with closely spaced natural frequencies is investigated. To achieve desired vibration reduction, a two-DOF DVA is connected to the beam through a pair of a spring and a dashpot. By introducing a virtual ground spring, the parameters of the absorber are determined via extended fixed point theory. The proposed method only requires univariate optimization and is computationally efficient. Numerical examples conducted verify the viability of the proposed method and the effectiveness of a two-DOF DVA in suppressing double resonances.
An Investigation on Flexural Fatigue Behavior of CFRP Quasi-Isotropic Laminates
Authors: Panbarasu K. , Ranganath V. R. , Prakash Raghu V.
Published: February 2021

In this study, AS4/914 grade carbon fibre reinforced plastic (CFRP) laminates with two different quasi-isotropic (QI) layup sequences are compared for their performance under four point bend flexure fatigue loads. The QI laminates were designated and fabricated as Laminate-1 (L1) [0/45/-45/90]2S and Laminate-2 (L2) [0/90/45/-45]2S, respectively. These laminates were designed, such that the 0° layers are placed at a similar position in both the laminate systems by changing the other layers. During the test, load and displacement data was monitored online along with instantaneous number of constant load amplitude (CLA) fatigue cycles to calculate the stiffness degradation. Three load levels of 90%, 80%, and 70% of the ultimate flexure strength (UFS) were chosen for assessing the flexure fatigue behavior of the laminates. A few tests were also attempted under variable amplitude loads: (i) high amplitude cycles followed by low amplitude and (ii) low amplitude cycles followed by high amplitude to examine load sequence effect on fatigue life, if any, as compared to the fatigue life under CLA. It has been observed that the laminate L1 performs better under higher amplitudes, while the laminate L2 shows increased life under lower load and variable amplitudes. The results obtained in the form of data plots and failure modes, supported by microscopic images, are discussed in the paper.
Mechanical Testing and Reliability Analysis for 3D Printed Cubic Lattices
Authors: Kulkarni Nitin Nagesh , Ekwaro-Osire Stephen , Egan Paul F.
Published: February 2021

3D printing has enabled new avenues to design and fabricate diverse structures for engineering applications, such as mechanically efficient lattices. Lattices are useful as implants for biological applications for supporting in vivo loads. However, inconsistencies in 3D printing motivates a need to quantify uncertainties contributing to mechanical failure using probabilistic analysis. Here, 50 cubic unit cell lattice samples were printed and tested with designs of 50% porosity, 500-micron beam diameters, and 3.5mm length, width, and height dimensions. The average length, width, and height measurements ranged from 3.47mm to 3.48mm. The precision in printing with a 95% confidence level was greater than 99.8%. Lattice elastic moduli ranged from about 270 MPa to 345 MPa, with a mean of 305 MPa. Probabilistic analyses were conducted with NESSUS software. The distributions of input parameters were determined using a chi-square test. The first-order reliability method was used to calculate the probability of failure and sensitivity of each input parameter. The elastic modulus was the most sensitive among all input parameters, with 57% of the total sensitivity. The study quantified printing inconsistencies and sensitives using empirical evidence and is a significant step forward for designing 3D printed parts for mechanical applications.
Measurement of Modes of Vibration of a Cultured Cell for its Mechanosensing Mechanisms
Authors: Sato Katsuya , Shiraishi Toshihiko
Published: February 2021

Applying mechanical vibration to cultured cells gives intracellular biochemical responses activated, for instance, their gene expression level is increased, so that it can be applied in the medical field. However, the cellular mechanisms of sensing mechanical vibration and transducing into the biochemical responses have not been clarified. One of the previous studies culturing osteoblastic cells under mechanical vibration showed that some of the intracellular biochemical responses reached peak depending on the frequencies like a resonance in the mechanical engineering field; the mRNA level of alkaline phosphatase at the frequency of 50 Hz reaches approximately 4.5 times as high as that at the control group [1]. Considering the analogy between the mechanical and the biochemical responses of a cell, the modes of vibration of a cell are thought to be related to the mechanosensing. In this study, the mode shapes of a single cell were experimentally measured under mechanical vibration up to 100 Hz using an improved experimental system with high natural frequencies designed to be low mass and high rigidity. This present paper will report the obtained experimental results of the mode shapes of a single cell nucleus and may contribute to the elucidation of the mechanosensing mechanisms of a cell for mechanical vibration.
Wet Gas Compressor Testing – Performance Uncertainty
Authors: Mæland Dagfinn , Bakken Lars E.
Published: February 2021

Based on experience from wet gas compressor testing at NTNU (low-pressure air-water fluid) and K-Lab full-scale testing (normal operating conditions, high pressure and hydrocarbon fluids), this paper documents important aspects relating to the uncertainty evaluation of wet gas compressor performance test results.

The Monte Carlo method for evaluation of uncertainty on a wet gas compressor system is outlined, and the resulting uncertainties of key compressor performance parameters are presented.

Furthermore, a sensitivity analysis has been performed to evaluate how uncertainties in the output of the model can be appointed to different sources of uncertainty in the inputs, thus identifying main contributors to the uncertainties.

The importance of accurately determining the fluid composition, the properties of the fluid components and how these affect the fluid characterization are discussed. Together with the choice of equation of state, the characterization directly affects the simulated fluid properties, and great care is required to obtain reliable compressor performance results.

Uncertainties of physical properties originating from the thermodynamic simulation show that compressor power and gas density ideally should be determined from direct measurements and not from thermodynamic simulations.
Estimation and Feasibility of Generating Power Using Tidal Energy
Authors: Paruchuru Satya Prasad , Koneti Siva Kalyani , Jammula Deepthi , Nuthalapati Jashwitha
Published: February 2021

Capturing the tidal energy is one of the ways of tapping natural and renewable energy which do not involve the cost of working fluid/ fuel. The present work focuses on some of the feasibility aspects of setting up of major tidal power plants along the seacoast. Besides, the present study synergizes on methods of estimating the power-producing capacities in regions along the seacoast. Estimation of power-producing capacities, calendar month-wise, and lunar month-wise gave handy information. Also, the estimation of power-producing capacities of different regions along a location gave clarity on the probable regions of interest for producing power simultaneously. A comparison of the estimates with the details of the literature authenticated the study. A discussion of producing more tidal power in specific locations gave insights into the aspects that may have been ignored in the literature. Geographic restrictions along the local seacoast like identifying the security-sensitive regions rationalized the estimating procedures. The paper includes a discussion of various factors that address the feasibility concerns. The study supposedly helps space exploration too.
The Use of Blogs in a Project-Based Learning Context for First-Year Engineering Students’ Teams
Authors: Alves Anabela C. , Pereira Ana C. , Leão Celina P. , Fernandes Sandra , Uebe-Mansur Andre F.
Published: February 2021

The Integrated Project of Industrial Engineering and Management 1 (IPIEM1) is a curricular unit of the first year developed in the first semester of the Integrated Masters degree of Industrial Engineering and Management (IEM11) – University of Minho, Portugal. In the 2019’s 1st semester and in the IPIEM1 previous versions, Project-Based Learning (PBL) was usually adopted as a learning methodology. In this pedagogical development context, freshman students develop a project integrating all five courses related to this current semester. To undertake this project, the students work in large teams that comprise nine to ten members. Throughout the semester, each team must accomplish the project phases and tasks. To communicate their progress and results developed during the semester, each team designed a blog. In the IPIEM1 previous editions of PBL of this year in this program, the weblog (blog) digital technology was also adopted, but it was never assessed. Thus, this paper has two main objectives: 1) to evaluate the importance of the blog for the teams; 2) to discuss teams’ engagement during its development, knowing that it would be a part of the assessment method. The survey results revealed that the teams considered the blog useful to keep an update record of the project progress and to stimulate the writing and reflection about project contents. Furthermore, some of teachers’ and students’ considerations showed the need for providing more training and experience in the development of blogs.
Investigating Acoustic Excitation and Reburn Interaction on NOx Concentration in Bio-Fuel Engines Exhaust
Authors: Abdul Shukoor Nellimala , Ali Mohamed I. Hassan , Thomas Rijo Jacob
Published: February 2021

Although gasoline and diesel fuels are likely to continue fuelling the internal combustion engines for the near future, there is an increasing concern over the emission of greenhouse gases and other environmental pollutants. Alternative fuels such as biofuels are promising as they are renewable, sustainable, and reduce engine emissions. However, nitric oxides (NO) and nitrogen dioxides (NO2) are typically released in greater proportion, generally known as NOx. Applying acoustic excitation on a biofuel operated engine exhaust gases is investigated with and without reburn. Four biofuels, namely Jatropha, Karanja, Palm and neem oils, are burned in a single-cylinder Internal Combustion Engine (ICE). The exhaust gases is carried out through a vertical tube where a trace of liquid petroleum gas (LPG) is injected before it passes an acoustic cross tube. Variable frequency acoustic waves were passed through the setup using a speaker and amplifier. NOx is sampled from the top of the vertical tube. Acoustic wave frequency, LPG reburn, and combination of both acoustic waves and reburn influence on NOx mitigation are investigated. The integration of acoustic wave excitation and reburn showed the most significant reduction in the NOx. The second-largest NOx reduction was achieved with the sole use of reburn technology. Integrating the acoustic excitation with reburning was found to produce about 80% NOx reduction at a range of 100–150 Hz for all tested biodiesel fuels. Out of the fuels under consideration, Neem Oil generated the lowest amount of NOx and showed 87% reduction in NOx.
Impact of the Gas Phase on the Properties of Foams
Authors: Pruvot Antoine Jean-Claude Jacques , Zhang Zhifeng , Conner Cathryn , McAndrew James
Published: February 2021

A better understanding of the impact of gas on foam can enable designing a foam system with desirable properties for applications ranging from enhanced oil recovery to preparation of food and beverages. In this work we have explored the effect of different gases on foam generation, coalescence and drainage using different pore-size spargers to vary bubble size. We have also demonstrated new measurements of foam drainage as a function of bubble size, and shown that they agree with a simple theoretical model. The results have potential benefits process improvement.
ROM of Superharmonic Resonance of Fourth Order of Electrostatically Actuated Clamped MEMS Circular Plates: Voltage Response
Authors: Caruntu Dumitru I. , Beatriz Julio
Published: February 2021

This paper investigates the voltage-amplitude response of superharmonic resonance of fourth order of electrostatically actuated clamped MEMS circular plates. The system consists of flexible MEMS circular plate parallel to a ground plate. Hard excitations (voltage large enough) and AC voltage of frequency near one eight of the natural frequency of the MEMS plate resonator lead it into a superharmonic resonance. Hard excitations produce actuation forces large enough to produce resonance away from the primary resonance zone. There is no DC component in the voltage applied. The partial differential equation of motion describing the behavior of the system is solved using two modes of vibration reduced order model (ROM). This model is solved through a continuation and bifurcation analysis using the software package AUTO 07P which produces the voltage-amplitude response (bifurcation diagram of the system, and a numerical integration of the system of differential equations using Matlab that produces time responses of the system. Numerical simulations are conducted for a typical MEMS silicon circular plate resonator. For this resonator the quantum dynamics effects such as Casimir effect or Van der Waals effect are negligible. Both methods show agreement for the entire range of voltage values and amplitudes. The response consists of an increase of the amplitude with the increase of voltage, except around the value of 4 of the dimensionless voltage where the resonance shows two saddle-node bifurcations and a peak amplitude about ten times larger than the amplitudes before and after the dimensionless voltage of 4. The softening effect is present. The pull-in voltage is reached at large values of the dimensionless voltage, namely about 14. The effects of damping and frequency on the voltage response are reported. As the damping increases, the peak amplitude decreases for the resonance. However, the pull-in voltage is not affected. As the frequency increases, the resonance zone is shifted to lower voltage values and lower peak amplitudes. However, the pull-in voltage and the behavior for large voltage values are not affected.
Computational Modeling of Combat Helmet Performance Analysis Integrating Blunt and Blast Loadings
Authors: Tan X. Gary , Bagchi Amit
Published: February 2021

Combat helmets have gone through many changes, from shells made of metal to advanced composites using Kevlar and Dyneema, along with introduction of pad suspensions to provide comfort and protection. Helmets have been designed to perform against ballistic and blunt impact threats. But, in today’s warfare, combat helmets are expected to protect against all three threats, blunt, ballistic impacts and blast effects to minimize traumatic brain injury (TBI) and provide a better thermal comfort. We are developing a helmet system analysis methodology integrating the effect of multiple threats, i.e., blast and blunt impacts, to achieve an optimal helmet system design, by utilizing multi-physics computational tools. We used a validated human head model to represent the warfighter’s head. The helmet composite shell was represented by an orthotropic elasto-plastic material model. A strain rate dependent model was employed for pad suspension material. Available dynamic loading data was used to calibrate the material parameters. Multiple helmet system configurations subjected to blast and blunt loadings were considered to quantify their influence on brain biomechanical response. Parametric studies were carried out to assess energy absorption for different suspension geometry and material morphology for different loadings. The resulting brain responses were used with published injury criteria to characterize the helmet system performance through a single metric for each threat type. Approaches to combine single-threat metrics to allow aggregating performance against multiple threats were discussed.
Dehumidification Strategies to Improve Energy Use at Retailers: A Case Study of a Supermarket Located in Guayaquil, Ecuador
Authors: Litardo Jaqueline , Hidalgo-León Rubén , Coronel Paul , Damian Andrea , Macías José , Soriano Guillermo
Published: February 2021

This study aims to model and evaluate the energy performance of a supermarket located in Guayaquil, Ecuador. For this purpose, we modeled the baseline of the supermarket using EnergyPlus software. All input parameters used in the simulations were provided by the supermarket staff. Air-conditioners and refrigerated cases were modeled using the default templates in EnergyPlus but replacing the specifications of the site systems. The baseline model predicted, within ±10%, the energy consumption of the case study when compared to the real electricity bills of the building. Then, we incorporated a desiccant wheel for each of the air-conditioner units that supply the frozen food area. Results showed relevant reductions of about 52% in cooling energy by decreasing the humidity level from 70% to 40% with the use of desiccant systems. However, the introduction of these systems increased the total building energy consumption by about 3% due to the regeneration process.
Initial Study Towards the Integrated Design of Bone Scaffolds Based on Cell Diffusion, Growth Factor Release and Tissue Regeneration
Authors: Sahin Mervenaz , Tabak Ahmet Fatih , Kiziltas Sendur Gullu
Published: February 2021

Three-dimensional (3D) porous tissue scaffolds combined with bioactive molecules and cells offer key advantages for bone repair mechanisms. A functional bone tissue scaffold should provide mechanical support with an adequate combination of porosity and permeability for nutrients, oxygen supply, waste removal, and growth factors release as well as controlled degradation. Although a vast amount of work exist to address these challenges, to the best of our knowledge, a design framework taking tissue differentiation, diffusion, and growth factor (GF) release into account in time-domain simultaneously does not exist. In this paper, we provide an initial effort to address such a need by laying down the foundations for a simulation framework incorporating these effects within a Finite Element Analysis (FEA) model in COMSOL Multiphysics® software. The effectiveness of the numerical model is demonstrated via preliminary mechano-biology analyses on a simulated 3D poroelastic bone scaffold. Initial time-dependent results demonstrate the suitability of this model for an optimization framework. More specifically, it is demonstrated that coupled Multiphysics equations of diffusion, GF release, and differentiation could provide valuable inputs for ideal bone scaffold systems for effective bone repair tasks in the future.
A Dynamic Battery State-of-Health Forecasting Model for Electric Trucks: Li-Ion Batteries Case-Study
Authors: Huotari Matti , Arora Shashank , Malhi Avleen , Främling Kary
Published: February 2021

It is of extreme importance to monitor and manage the battery health to enhance the performance and decrease the maintenance cost of operating electric vehicles. This paper concerns the machine-learning-enabled state-of-health (SoH) prognosis for Li-ion batteries in electric trucks, where they are used as energy sources. The paper proposes methods to calculate SoH and cycle life for the battery packs. We propose autoregressive integrated modeling average (ARIMA) and supervised learning (bagging with decision tree as the base estimator; BAG) for forecasting the battery SoH in order to maximize the battery availability for forklift operations. As the use of data-driven methods for battery prognostics is increasing, we demonstrate the capabilities of ARIMA and under circumstances when there is little prior information available about the batteries. For this work, we had a unique data set of 31 lithium-ion battery packs from forklifts in commercial operations. On the one hand, results indicate that the developed ARIMA model provided relevant tools to analyze the data from several batteries. On the other hand, BAG model results suggest that the developed supervised learning model using decision trees as base estimator yields better forecast accuracy in the presence of large variation in data for one battery.
Thermal and Electrical Performance Analysis of a Novel Medium Concentration Dual Photovoltaic System for Different Phase Change Materials
Authors: Hasnain Arshmah , Sarwar Jawad , Abbas Qamar , Younas Muhammad Azeem , Kakosimos Konstantinos E.
Published: February 2021

In this work, performance analysis of a medium concentrated photovoltaic system employing two mono-facial cells is carried out using a validated finite element based coupled optical, electrical, and thermal model. The environmental conditions of Lahore, Pakistan are considered, and the system is thermally regulated with a phase change material. Nine commercially available phase change materials (PCM) having melting temperature ranges between 41–65°C are selected. These PCMs include LA, RT47, S-series salt, ClimSel™ C48, STL47, RT54, RT60, RT62, and RT64. Temperature regulation, melt fraction, thermal and electrical efficiency are determined for each material for four months of January, March, July, and September representing four seasons of a year. The comparison of the materials has shown that S-series salt and C48 melt completely during the day and regenerate to solid-phase during night in the whole year except January. But S-series salt is found to be most suitable in current configuration due to its higher overall efficiency over the whole year.
Application of Random Forest Machine Learning Models to Forecast Combustion Profile Parameters of a Natural Gas Spark Ignition Engine
Authors: Liu Jinlong , Ulishney Christopher , Dumitrescu Cosmin E.
Published: February 2021

Predicting internal combustion (IC) engine variables such as the combustion phasing and duration are essential to zero-dimensional (0D) single-zone engine simulations (e.g., for the Wiebe function combustion model). This paper investigated the use of random forest machine learning models to predict these engine combustion parameters as a modality to reduce expensive engine dynamometer tests. A single-cylinder four-stroke heavy-duty spark-ignition engine fueled with methane was operated at different engine speeds and loads to provide the data for training, validation, and testing the proposed correlated model. Key engine operating variables such as spark timing, mixture equivalence ratio, and engine speed were the model inputs. The performance of the models was validated by comparing the prediction dataset with the experimentally measured results. Results showed that the prediction error of the random forest machine learning algorithm was acceptable, suggesting that it can be used to predict the combustion parameters of interest with acceptable accuracy.
Prediction of Efficient Operating Conditions Inside a Heavy-Duty Natural Gas Spark Ignition Engine Using Artificial Neural Networks
Authors: Liu Jinlong , Ulishney Christopher , Dumitrescu Cosmin E.
Published: February 2021

Research engines with optical access can assist traditional engine development and optimization by providing first-hand information of in-cylinder combustion process. However, the fragility of the optical engine components (e.g., the see-thru windows are usually made from fused silica) limit the engine operating conditions such as the maximum in-cylinder pressure and pressure rise rate. To make it easier to determine if a particular engine operating condition can be used for optical investigations, a back-propagation artificial neural network model was built to provide the values of pressure-based parameters of interest for engine safety. The training data came from steady-state engine experiments that changed spark timing, mixture equivalence ratio, and engine speed, but using the non-optical configuration of the engine to widen the testing conditions. The comparison between model predictions and experimental data indicated that the well-trained artificial neural network model can provide fast and consistent results, making it an easy-to-use tool for designing future optical engine investigations.