bluuebunny/crossref_metadata_2025 huggingface dataset:
Ventricular tachycardia induced by a backup pacing stimulus in a patient with a dual chamber pacemaker with AutoCapture
Authors: Greenspon Arnold J. , Frisch Daniel R. , Ho Reginald T. , Pavri Behzad B.
Published: February 2021

Manufacturers of cardiac implantable electronic devices have incorporated automatic features to allow for remote monitoring, improve device longevity, and additional safety. Algorithms to automatically measure capture threshold and adjust output to preserve battery life are one such feature. Automatic features may occasionally result in unexpected or undesirable clinical outcomes. We report on a patient who developed ventricular tachycardia inadvertently induced by the AutoCapture. feature of an Abbott/St. Jude Medical (SJM) pacemaker.
Insights intoanti‐Dformation in carriers ofRhDvariants through studies of3Dintraprotein interactions
Authors: Floch Aline , Pirenne France , Barrault Aurélie , Chami Btissam , Toly‐Ndour Cécile , Tournamille Christophe , de Brevern Alexandre G.
Published: February 2021

Background

Many RhD variants associated with anti‐D formation (partial D) in carriers exposed to the conventional D antigen carry mutations affecting extracellular loop residues. Surprisingly, some carry mutations affecting transmembrane or intracellular domains, positions not thought likely to have a major impact on D epitopes.

Study Design and Methods

A wild‐type Rh trimer (RhD1RhAG2) was modeled by comparative modeling with the human RhCG structure. Taking trimer conformation, residue accessibility, and position relative to the lipid bilayer into account, we redefine the domains of the RhD protein. We generated models for RhD variants carrying one or two amino acid substitutions associated with anti‐D formation in published articles (25 variants) or abstracts (12 variants) and for RHD*weak D type 38. We determined the extracellular substitutions and compared the interactions of the variants with those of the standard RhD.

Results

The findings of the three‐dimensional (3D) analysis were correlated with anti‐D formation for 76% of RhD variants: 15 substitutions associated with anti‐D formation concerned extracellular residues, and structural differences in intraprotein interactions relative to standard RhD were observed in the others. We discuss the mechanisms by which D epitopes may be modified in variants in which the extracellular residues are identical to those of standard RhD and provide arguments for the benignity of p.T379M (RHD*DAU0) and p.G278D (RHD*weak D type 38) in transfusion medicine.

Conclusion

The study of RhD intraprotein interactions and the precise redefinition of residue accessibility provide insight into the mechanisms through which RhD point mutations may lead to anti‐D formation in carriers.
Factors driving availability of COVID‐19 convalescent plasma: Insights from a demand, production, and supply model
Authors: Russell W. Alton , Grebe Eduard , Custer Brian
Published: February 2021

Background

COVID‐19 Convalescent Plasma (CCP) is a promising treatment for COVID‐19. Blood collectors have rapidly scaled up collection and distribution programs.

Methods

We developed a detailed simulation model of CCP donor recruitment, collection, production, and distribution processes. We ran our model using varying epidemic trajectories from 11 U.S. states and with key input parameters drawn from wide ranges of plausible values to identify key drivers of ability to scale collections capacity and meet demand for CCP.

Results

Utilization of available CCP collections capacity followed increases in COVID‐19 hospital discharges with a lag. Utilization never exceeded 75% of available capacity in most simulations. Demand was met for most of the simulation period in most simulations, but a substantial portion of demand went unmet during early, sharp increases in hospitalizations. For epidemic trajectories that included multiple epidemic peaks, second wave demand could generally be met due to stockpiles established during the decline from an earlier peak. Apheresis machine capacity (number of machines) and probability that COVID‐19 recovered individuals are willing to donate were the most important supply‐side drivers of ability to meet demand. Recruitment capacity was important in states with early peaks.

Conclusions

Epidemic trajectory was the most important determinant of ability to meet demand for CCP, although our simulations revealed several contributing operational drivers of CCP program success.
Influence of muscle‐sparing lateral thoracotomy on postoperative pain and lameness: A randomized clinical trial
Authors: Nutt Anna E. , Knowles Toby G. , Nutt Neil G. , Murrell Joanna C. , Carwardine Darren , Meakin Lee B. , Chanoit Guillaume
Published: February 2021

Objective

To assess and compare the magnitude of lameness and level of pain after muscle‐sparing lateral thoracotomy (MSLT) and standard lateral thoracotomy (SLT) in dogs.

Study design

Randomized, blinded, prospective clinical study.

Animals

Twenty‐eight client‐owned dogs.

Methods

The latissimus dorsi muscle was retracted in the MSLT group and was transected in the SLT group. Gait was analyzed with a force plate, and the peak vertical force symmetry index (SI) was calculated within 24 hours before surgery, 3 days postoperatively, and 8 to 12 weeks postoperatively. Symmetry index and pain scores as measured by the Glasgow Composite Measure Pain Scale ‐ Short Form were assessed as primary outcome measures.

Results

The SI 3 days postoperatively was lower compared with the preoperative SI value in all dogs, consistent with lameness of the ipsilateral thoracic limb (P < .001). The absolute differences in preoperative and 3‐day‐postoperative SI provided evidence that this change was 3.1‐fold greater after SLT compared with after MSLT (P = .009). Pain scores 1 day after surgery were lower after MSLT (1) compared with after SLT (2.5,P < .001).

Conclusion

Lateral thoracotomies caused postoperative pain and ipsilateral forelimb lameness, and both were reduced by sparing the latissimus dorsi.

Clinical significance

Sparing the latissimus dorsi should be considered to decrease immediate postoperative morbidity in dogs undergoing lateral thoracotomy.
Buckling of Flat Curved Bars and Slightly Curved Plates
Authors: Timoshenko S.
Published: February 2021

This paper considers the case of the flat arch and the slightly curved plate, with uniformly distributed load, which may fail not as a result of high stresses and yielding of the material but because of instability, and it is shown how the critical load at which buckling occurs may be calculated. The case of the bimetallic strips used as part of thermostats is also considered.
Investigating the Effect of Axial Compression and Distraction on Cervical Facet Mechanics During Supraphysiologic Anterior Shear
Authors: Quarrington Ryan D. , Costi John J. , Freeman Brian J. C. , Jones Claire F.
Published: February 2021

Bilateral cervical facet dislocation (BFD) with facet fracture (Fx) often causes tetraplegia but is rarely recreated experimentally, possibly due to a lack of muscle replication. Intervertebral axial compression (due to muscle activation) or distraction (due to inertial loading), when combined with excessive anterior translation, may influence interfacet contact or separation and the subsequent production of BFD with or without Fx. This paper presents a methodology to produce C6/C7 BFD+Fx using anterior shear motion superimposed with 300 N compression or 2.5 mm distraction. The effect of these superimposed axial conditions on six-axis loads, and C6 inferior facet deflections and surface strains, was assessed. Twelve motion segments (70 ± 13 yr) achieved 2.19 mm of supraphysiologic anterior shear without embedding failure (supraphysiologic shear analysis point; SSP), and BFD+Fx was produced in all five specimens that reached 20 mm of shear. Linear mixed-effects models (α = 0.05) assessed the effect of axial condition. At the SSP, the compressed specimens experienced higher axial forces, facet shear strains, and sagittal facet deflections, compared to the distracted group. Facet fractures had similar radiographic appearance to those that are observed clinically, suggesting that intervertebral anterior shear motion contributes to BFD+Fx.
Improving Ambient Contrast Ratio and Color Uniformity of Mini Full Color Light-Emitting Diodes Using an SiO2/Graphite Bilayered Packaging Structure
Authors: Li Zong-Tao , Wu Jun-Hao , Ren Zhi-yao , Song Yao-xing , Li Jia-Sheng
Published: February 2021

Mini full-color light-emitting diodes (mini-fc-LEDs) are a promising solution for display applications, including outdoor, cinema, and wearable devices, owing to their high resolution. However, it is difficult to simultaneously obtain high color uniformity and ambient contrast ratio (ACR). To solve this issue, we report a bilayered packaging structure with an SiO2 scattering layer on the bottom and a graphite extinction layer on the top. The bilayered packaging structure combines the scattering effect of SiO2 nanoparticles and the extinction effect of graphite nanoparticles, wherein the scattering effect improves the color uniformity, and the extinction effect improves the ACR. The color uniformity and ACR of the mini-fc-LEDs were selectively adjusted by changing the nanoparticle concentration and the thickness ratio of the bilayer. Compared to conventional devices, the inhomogeneity of the bilayered devices reduced by 65.9%, the ACR increased by 32.9%, and the figure of merit (FOM, representing the overall performance of the device) increased by 168.8%. We believe that the proposed packaging structure can also be applied to other LEDs such as OLEDs and micro-LEDs.
Effects of Antimony Deposition on Field-Emission Current Density of Ge/Si
Authors: Burobina Veronika
Published: February 2021

To estimate the field-emission current density of a Ge/Si heterosystem, 20-nm germanium/silicon (100) samples were grown by molecular beam epitaxy. The surface of one sample was covered with a layer of antimony, which was removed in vacuum prior to the samples being measured. A second sample of Ge/Si was exposed to room air in the absence of antimony. The current–voltage characteristics of both samples obtained by scanning tunneling microscopy (STM) were discovered to be in agreement with classical Fowler–Nordheim theory. The density of emission current from Ge nanocrystal exceeds the density of emission current from the wetting layer of Ge/Si. The density of emission current of pure Ge nanocrystal is less than the density of emission current of Ge nanocrystal with adsorption layers.
Performance Investigation of a Vapor Adsorption Refrigeration System Based on Adsorption/Desorption Time and Heat Transfer
Authors: Pendurthi Manudeep , Pelluru Vamsi Bhargav , Chilakapati Anjaneyulu , Dandotiya Devendra , Banker Nitin D.
Published: February 2021

In the past two decades, the development of sustainable refrigeration systems such as thermally operated vapor adsorption refrigeration systems achieved unparalleled growth in the research world as compared to conventional vapor compression systems and even thermally operated vapor absorption refrigeration system. Yet, the commercial success of the adsorption refrigeration system could not be achieved due to mainly its higher space area required per kilowatts of refrigeration capacity. With the focus to look improvement on this issue, the performance of the adsorption refrigeration system has been studied concerning adsorption/desorption time and heat transfer of adsorber. It is proposed to reduce the adsorption/desorption time, due to which the concentration (ratio of the mass of adsorbed refrigerant to the mass of activated carbon) will not reach its equilibrium value, but it is possible to get a higher mass flow in a shorter period. In turn, the cooling capacity will increase. In view of this, a mathematical model has been developed to study the performance and applied to three adsorbent–adsorbate pairs, namely, Maxsorb III–ethanol, Maxsorb III–R507a, and Maxsorb III–R134a. Based on the mathematical investigations, it is observed that the cooling capacity can be improved significantly at a litter higher cost of the heat transfer mechanism.
Effect of Spatially Varying Magnetic Field on the Cooling of an Electronic Component by Natural Convection With Magnetic Nanofluids
Authors: Kumar Deepak , Kumar Aditya , Subudhi Sudhakar
Published: February 2021

Natural convection cooling of an electronic component in an electronic device using water-based Fe3O4 magnetic nanofluids is studied under the presence of the magnetic field. The heated vertical electronic component in an enclosure type electronic device with a magnetic field source is used as a model for the study. Different samples of Fe3O4-water nanofluid are prepared using different surfactants and the stability of those samples are estimated using visualization and zeta potential technique. Thermal properties of the stable sample of magnetic nanofluid are precisely measured. The experimentally measured properties are used for further theoretical study. The natural convection is characterized in terms of the relative position of the magnetic source and the electronic component, the strength of the magnetic field, and the magnetization of the nanofluids. Nine different combinations of the position of the magnetic source and the electronic component have been compared with the case in which there is an absence of the magnetic field. The dimensionless number used in this investigation are Rayleigh number (103 ≤ Ra ≤ 106), magnetic numbers (Mn = 100, 500, and 1000), and Hartmann Number (0 ≤ Ha ≤ 100). The position of the magnetic source with respect to the electronic component significantly affects the rate of heat transfer. The effect is more pronounced when the magnetic source is placed below any of the two vertical walls of the enclosure. The fluid flow is observed distorted near the magnetic source when the Ha is increased. The increment in the magnetic number strengthens the flow, which leads to the enhanced heat transfer rate.
The Innovation Bank: Blockchain Technology and the Decentralization of the Engineering Professions
Authors: Robles Daniel R. , Layton Bradley Edward
Published: February 2021

The Innovation Bank is a novel business method that integrates and capitalizes knowledge assets. The Innovation Bank is an application of game theory, actuarial math and a simple native “proof-of-stake” blockchain. The system aims to unify the global engineering and scientific disciplines by incentivizing individual practitioners to form knowledge asset networks among each other by producing claims and validations related to observable and measurable events. Each claim and associated validation forms a node in a network for which each participant is awarded a cryptographic token memorializing earned stake (equity) in the system. A secure, validated, and decentralized knowledge repository and access management system is secured by a simple native blockchain. Revenue is generated through the liquidation of earned tokens on an external market to third parties seeking access to network metadata for business intelligence. The intrinsic value of the network grows as the number of participants increases. As participation increases, the quantity and quality of the transaction records also increases. Third-party buyers may include banks, insurance companies, and private enterprise.
A GFEM With Local Gradient Smoothed Approximation for 2D Solid Mechanics Problems
Authors: Tang Jinsong , Qian Linfang , Chen Guangsong
Published: February 2021

In this paper, a generalized finite element method (GFEM) with local gradient smoothed approximation (LGS-GFEM) using triangular meshes is proposed. The displacement field function of LGS-GFEM consists of the finite element shape function and the node displacement function. In order to obtain the nodal displacement function, the second order Taylor expansion is considered. The derivative term in Taylor expansion is obtained by using gradient smoothed technique in a smoothed domain. The displacement in smoothed operation is interpolated by polynomial basis function and radial basis function. Two kinds of integration schemes are considered, i.e. LGS-GFEM-I and LGS-GFEM-II respectively. The smoothed composite shape function of LGS-GFEM retains the ideal Kronecker property of the finite element shape function. Besides, the proposed LGS-GFEM has some other important properties such as no extra DOFs, linear independent, etc. The superiority of LGS-GFEM including high accuracy, rapid error convergence and temporal stability, is demonstrated by two representative numerical examples of static and free vibration, and compared with the classical finite element of triangular (FEM-T3) and quadrilateral (FEM-Q4) elements.
The Design and Implementation of a Heat Transfer System for the Pyrolysis of Synthetic Polymers
Authors: Elsharafi Mahmoud , Walsh Sheldon , Fields Brandy , Acuna Caleb , La Fleur Okan , Statham William
Published: February 2021

Plastic trash has been building up for over a century in our landfills and oceans. Not only does it affect our wildlife, but the trash affects our lives by changing our oceans, our weather currents, and our food supply. To truly deplete the plastics that fill our landfills and oceans, a cost-effective and profitable method of plastic disposal, should be created.

The heat transfer system will be used to heat plastics in such a way to break apart the polymer chains via pyrolysis, creating a vapor. The vapor will then be cooled where it will create petroleum oil, wax, and gaseous byproduct. This project research will continue by redesigning the furnace used in previous research, to get an accurate more stable heat that will reach the necessary boiling point of the plastics to create the vapor. Vapor will be collected through pipes and routed to a cooling unit, where it will be condensed, creating petroleum oil, a solid wax, and gaseous byproducts.

Further research for oil optimization using variables such as types of plastics, temperature magnitudes and temperature rates from pyrolysis of synthetic polymers will aid in the creation of commercial/industrial sized pyrolysis systems that will be ecofriendly and economical.
Mobile Carrying Platform: i-Explore
Authors: Sohn Kiwon , Emami Aurian , Yang Jaesung
Published: February 2021

This paper presents the development of mobile transportation robot, i-Explore which has been designed and built by ART (Assistive Robot Team) in University of Hartford since 2018. The main objective of i-Explore is to assist and carry children who have severe physical disabilities in indoor environments, especially for domestic uses. In this paper, the mechanical design and building processes of i-Explore which focused on fast reactiveness and low-cost manufacturing as its main technical design requirements are described first. Then, the kinematic analysis and its implementation in the low-level body controller of the mobile robot are described. Lastly, i-Explore is tested and evaluated both in cleaned and cluttered works spaces with its semi-autonomous motions which are designed for the robot’s navigation in human centered environments.
Thermal Energy Replacement Potential in a Slaughter Plant From Rumen Pellets
Authors: Fajardo J. , Barreto D. , Morales O.
Published: February 2021

In this work, steam generation was studied using natural gas or rumen as energy sources in a slaughter plant that sacrifices 7500 cattle per month, with consumption 0.5749 kg/s of saturated steam at 624 kPa. For a slaughtered cow, 10.5 kg of rumen can be obtained after being dried outdoors; for its final disposal, the slaughter plant bears the costs of USD 7.2 per ton of rumen. In the study, exergy and exergoeconomic performances were compared by generating steam with a natural gas boiler with the steam generation with a rumen boiler. From this, combustion analysis, energy efficiency, exergy destruction, exergy efficiency, exergy destruction costs, and generating 1 kg of steam from the two boilers were evaluated. The study results showed that the generation of steam with rumen is less efficient than with natural gas since it presents the exergy destruction of 1175.9 kW and exergy efficiency of 26.83%. While the generation of steam with rumen boiler was obtained, with exergy destruction of 1419.9 kW and exergy efficiency of 23.29%. Exergy destruction cost and the cost of generating 1 kg of steam using rumen were $/h 7821 and 0.0073 $/kg, respectively. Although the generation of steam with natural gas present the exergy destruction cost of 26285 $/h and the cost of generating steam of 0.021 $/kg, this indicators are higher using natural gas as a fuel that with rumen pellets.
Stamp Forming: A Comparison in the Use of Draw Beads and Blank Holder Force for Producing Aluminum Panels
Authors: Emblom William J.
Published: February 2021

An investigation was performed examining the effects of draw beads and blank holder forces on local forces in various regions of a stamp forming process that produced oval aluminum panels. The results showed that provided there was sufficient blank holder forces to prevent wrinkling, the regions with draw beads were affected more by draw bead height than by blank holder force. However, at the die ends, away from the draw beads, blank holder force had more of an effect than the draw beads did with respect to local forces. Additionally, the draw bead height effects at the die end were not directly related but had to be interpreted based upon the effect on strains within the flange region at the die ends. This study may be especially useful for researchers in the automotive sector who are particularly interested in aluminum panel forming.
Evaluating the Influence of Nanofluid Type and Volume Fraction on the Performance of Heat Exchanger
Authors: Jassim Esam I. , Ahmed Faizan , Jasem Bashar
Published: February 2021

The utilization of nanofluid in heat exchanger is of immense interest in the petrochemical and power plant industries due to the durability provided to the exchanger long-life operation. In the present research, an experimental investigation is carried out to study the existence of copper and aluminum oxide nanoparticles in the base fluid and their impact on the performance of the heat exchanger. A comparison with the theoretical outcome is also conducted. Pure water is pumped through the tubes of the heat exchanger unit whereas the nanofluid is pumped into the shell of the unit by means of another impeller pump. Various volume fractions ranging from 0.26%–0.83% are tested to assess the morphology of nanoparticle and volume fraction on the exchanger efficiency. It is observed that the volume fraction of nanofluid has a significant positive impact on the effectiveness of the heat exchanger. An increase in the volume fraction of the nanofluid enhances the effectiveness of the heat exchanger up to 7% for Al2O3 and 10% for Copper. The impact of the Reynolds number is also studied. The Reynolds number for the cold-side nanofluid varies in the range 7000–15000. As the Reynolds number augments, the Nusselt number also increases by ∼13% for Al2O3 and 23% for Cu nanofluids. Additionally, the effect of varying inlet temperatures of hot fluid is investigated. The results indicate an enhancement in the exchanger performance at higher inlet temperatures of the hotside fluid.
The Flow Dynamics of Stranded Cables
Authors: Abdelhady Mohamed , Wood David H.
Published: February 2021

Only a few studies of the flow dynamics of stranded cables have been made despite their wide applications. This paper studies in detail the wake flow dynamics of two stranded cables using Particle Image Velocimetry at Reynolds number of 1,500. First and second order statistics were obtained for both cables. Besides, Proper Orthogonal Decomposition of the velocity and vorticity fields was used to determine the effect of the strands on the coherent structures. Results showed that wake flow dynamics are significantly affected by cable strands, specially as the ratio of cable overall diameter to strand diameter increases. Finally, this study provides detailed stranded cables wake flow dynamics. Such understanding could be used in optimizing cable design for different applications, to allow, for example, overhead transmission lines to passively increase their current carrying capacity.
Effect of the Environmental Conditions of Tropical Climates on the Performance Parameters of a Gas Turbine Power Generation Plant
Authors: Fajardo J. , Barreto D. , Castro T. , Baldiris I.
Published: February 2021

It is known that high temperatures adversely affect the performance of gas turbines, but the effect of the combination of atmospheric conditions (temperature and relative humidity -RH-) on the operation of this type of system is unknown. In this work the effects of atmospheric conditions on the energy and exergy indicators of a power plant with gas turbine were studied. The indicators studied were the mass flow, the specific work consumed by the compressor, specific work produced by the turbine, the combustion gas temperature, the NO concentration, the net output power, the thermal efficiency, the heat rate, the specific consumption of fuel, the destruction of exergy and exergy efficiency. Among the results, it is noted that for each degree celsius that reduces the temperature of the air at the compressor inlet at constant relative humidity on average, the mass flow of dry air increases by 0.27 kg/s, the specific work consumed by the compressors decreases by 0.45%, the output power increases by 1.17% and the thermal efficiency increases by 0.8%, the exergy destruction increases by 0.72% and the exergy efficiency increases by 0.81%. In addition, humidity changes relative to high temperatures are detected more significantly than at low temperatures. The power plant studied is installed in Cartagena, Colombia and since it is not operating in the design environmental conditions (15 °C and 60% relative humidity) it experiences a loss of output power of 6140 kW and a drop in thermal efficiency of 5.12 %. These results allow considering the implementation of air cooling technologies at the compressor inlet to compensate for the loss of power at atmospheric air conditions.
A Numerical Simulation of Unsteady Lid Driven Cavity Flow With Moving Boundaries Using CMSIP
Authors: Akyuzlu K. M. , Antoniou A.
Published: February 2021

A two-dimensional, mathematical model is adopted to investigate the development of circulation patterns for compressible lid driven flows inside a rectangular cavity where the bottom of the cavity is free to move at a specified speed. A time and space dependent transformation is applied to the governing equations to obtain a rigid (non-moving) solution domain. The transformed equations are discretized for a uniform and orthogonal computational mesh using second order in space and first order in time finite difference schemes. The resulting nonlinear equations are then linearized using Newton’s linearization method. Finally, the set of algebraic equations that result from this process are put into a matrix form and solved using the Coupled Modified Strongly Implicit Procedure (CMSIP). Numerical experiments are carried out for various Reynolds numbers to verify the accuracy of the solution algorithm. Then the numerical simulations of lid driven flow inside the cavity is carried out for the unsteady case where the aspect ratio of the cavity is changed from 1 to 1.5 at a constant speed. It is concluded that the proposed model is successful in predicting the unsteady characteristics of the primary vortex and the secondary vortices inside a cavity with moving bottom.
Infill Defective Detection System Augmented by Semi-Supervised Learning
Authors: Song Jinwoo , Moon Young B.
Published: February 2021

In an effort to identify cyber-attacks on infill structures, detection systems based on supervised learning have been attempted in Additive Manufacturing (AM) security investigations. However, supervised learning requires a myriad of training data sets to achieve acceptable detection accuracy. Besides, since it is impossible to train for unprecedented defective types, the detection systems cannot guarantee robustness against unforeseen attacks.

To overcome such disadvantages of supervised learning, This paper presents infill defective detection system (IDDS) augmented by semi-supervised learning. Semi-supervised learning allows classifying a sheer volume of unlabeled data sets by training a comparably small number of labeled data sets. Additionally, IDDS exploits self-training to increase the robustness against various defective types that are not pre-trained.

IDDS consists of the feature extraction, pre-training, self-training. To validate the usefulness of IDDS, five defective types were designed and tested with IDDS, which was trained by only normal labeled data sets. The results are compared with the basis accuracy from the perceptron network model with supervised learning.
Pulse Shaping in 1D Elastic Waveguides for Shock Testing
Authors: Johnson William R. , Leamy Michael J. , DeLima Washington , Ruzzene Massimo
Published: February 2021

Mechanical shock events experienced by electronics systems can be reproduced in the laboratory using Hopkinson bar tests. In these tests a projectile strikes a bar, creating a pulse which travels through the bar into the system. The quality of these tests depends on the closeness of the shape of the incident pulse to the shape specified for the test. This paper introduces a new way to control the shape of the incoming pulse, through the use of elastic metamaterial concepts. Two dispersion-modifying material concepts, phononic crystals, and local resonators, are examined for their wave shaping capabilities in 1D elastic waveguides. They are then evaluated using a transfer matrix method to determine the output wave shape in the time domain. The concepts are then optimized for various pulse shapes, showing that they are most effective when they are tuned to introduce dispersion near the fundamental frequency of the incident wave.
Numerical Modelling for Oblique Impacts With Ductile Material Particle Erosion During Cold Gas Dynamic Spray
Authors: Oyinbo Sunday Temitope , Jen Tien-Chien , Aasa Samson A.
Published: February 2021

Another key parameter that affects the coating deposition efficiency of cold gas dynamic spray technology is the contact angle. The particle tangential sliding on the substrate at impact is due to the gas flow bow shock at a supersonic velocity which is liable for the erosion at the surface of the substrate. This study presented a finite element approach of a numerical model to investigate the profile of the deformed sprayed particles under the condition of oblique impact and the erosion mechanism for solid particle impact on ductile material during Cold Gas Dynamic spray. In the numerical modelling of cold gas dynamic spray (CGDS) by a Lagrangian approach that was developed, oblique erodent particle on the substrate at controlled contact angle (10°–90°), velocity (500 m/s) and friction coefficient (0.3) was simulated. It was discovered that in the substrate, the crater depth decreases as well as the area of contact between the substrate and the deformed particles when the contact angle increases at the same impacting conditions. The material removal and crack formation mechanism were also simulated successfully by the accumulation of residual strain that resulted in the dynamic detachment of material elements at the surface as they fail.
Analysis of Composite Bolted Connection Joints Under Out of Plane Loading
Authors: Mahmoud Hassan A. , Shazly Mostafa , Bahei-El-Din Yehia , El-Kashif Emad
Published: February 2021

The use of composite joints has been increased in recent years in structural applications such as aircraft, civil engineering structure, ship structure, wind energy sector, and automotive industry. In this paper, the behaviour of composite bolted connection joints under out of plane loading is investigated. A parametric study was conducted to study the joint stiffness variation with various geometric parameters, which include the edge distance, bolt diameter, plate width, and the laminate stacking sequence. The experimental work was conducted on GFRP tension clips (L-angle) joint specimens manufactured by the vacuum infusion technique. In the present work, two types of laminates were used, unidirectional laminates [0°]5 with an areal density of 1050 gm/m2, triaxial laminates [−45°/+45°/0°]5 with an areal density of 1200 g/m2. A 3D finite element (FE) model was developed to study the effect of joint parameters on its stiffness. Finite element models were constructed, and the experimental results were used to validate the finite element models. The analysis concluded that the failure load increases when the edge distance to bolt diameter ratio (E/D) increases and the triaxial stacking sequence is better than unidirectional. The (E/D) ratio, the (W/D) ratio and stacking sequence were found to be very significant parameters.
Ultrasonic Nondestructive Testing for In-Line Monitoring of Wire-Arc Additive Manufacturing (WAAM)
Authors: Hossain Md Shahjahan , Taheri Hossein , Pudasaini Niraj , Reichenbach Alexander , Silwal Bishal
Published: February 2021

The applications for metal additive manufacturing (AM) are expanding. Powder-bed, powder-fed, and wire-fed AM are the different kinds of AM technologies based on the feeding material. Wire-Arc AM (WAAM) is a wire-fed technique that has the potential to fabricate large-scale three-dimensional objects. In WAAM, a metallic wire is continuously fed to the deposition location and is melted by an arc-welding power source. As the applications for WAAM expands, the quality assurance of the parts becomes a major concern. Nondestructive testing (NDT) of AM parts is necessary for quality assurance and inspection of these materials. The conventional method of inspection is to perform testing on the finished parts. There are several limitations encountered when using conventional methods of NDT for as-built AM parts due to surface conditions and complex structure. In-situ process monitoring based on the ultrasound technology is proposed for WAAM material inspection during the manufacturing process. Ultrasonic inline monitoring techniques have the advantages of providing valuable information about the process and parts quality. Ultrasonic technique was used to detect the process condition deviations from the normal. A fixture developed by the authors holds an ultrasonic sensor under the build platform and aligned with the center of the base plate. Ultrasonic signals were measured for different process conditions by varying the current and gas flow rate. Features (indicators) from the radio frequency (RF) signal were used to evaluate the difference in signal clusters to identify and classify different build conditions. Results show that the indicator values of the ultrasonic signals in the region of interest (ROI) changes with different process conditions and can be used to classify them.
Controlling Drag and Down Forces on a Vehicle Side-View Mirror by Applying Vortex Generator Designs on the Bottom Surface
Authors: Dong Zulong , Jawad Badih , Liu Liping , Metwally Hossam
Published: February 2021

Side-view mirrors impact the aerodynamic performance of a vehicle due to the creation of extra drag force, noise, and vibration. This paper presents an alternative practical solution for improving aerodynamic performance of vehicle side-view mirrors. A CFD analysis is conducted for studying the airflow around a side-view mirror with different types of passive vortex generators (VGs) mounted on the bottom surface. VGs are small wingtips that are used to produce swirling motion in the flow stream. In recent years, VGs have been used in vehicle underbody diffusers to delay flow separation and to increase the flow control surface. This study aims to understand the effect of underbody VGs on the flow mechanisms downstream of the side-view mirror, and its impact on both drag and down forces.

The turbulent flow behind the side-view mirror is investigated to determine the effects of different VG types and attack angles. Four types of VGs are considered in this work. Changes are made to the baseline model by either adding the VGs close to the frontal edge of the bottom surface of the mirror which aims to control the flow separation, or adding the VGs close to the back edge which aims to reduce the shedding area. Computational Fluid Dynamics (CFD) analysis using ANSYS Fluent is conducted to simulate the flow behavior by using three dimensional Reynolds-averaged Navier-Stokes method with standard K-epsilon (K-ε) turbulence model. In order to incorporate the effect of vehicle body, each model is assembled on a quad-vehicle bluff body for analysis. The drag and down forces are numerically solved and compared with the results of the baseline model at the speeds of 15, 40, 60 and 80 miles per hour. It is concluded from the CFD analysis that: (1) Mounting VGs at the bottom surface of a side-view mirror reduces down force in most cases. (2) Setting underbody VGs at either the front or back edge of the mirror bottom surface has a slight effect on reducing drag force. (3) Multiple types of VGs show improved results with a 30 degree attack angle, which encourages future studies of VG applications with large attack angles.
Virtual Simulations Environment Development for Autonomous Vehicles Interaction
Authors: Malayjerdi Mohsen , Kuts Vladimir , Sell Raivo , Otto Tauno , Baykara Barış Cem
Published: February 2021

One of the primary verification criteria of the autonomous vehicle is safe interaction with other road users. Based on studies, real-road testing is not practical for safety validation due to its time and cost consuming. Therefore, simulating miles driven is the only feasible way to overcome this limitation. The primary goal of the related research project is to develop advanced techniques in the human-robot interaction (HRI) safety validation area by usage of immersive simulation technologies. Developing methods for the creation of the simulation environment will enable us to do experiments in a digital environment rather than real. The main aim of the paper is to develop an effective method of creating a virtual environment for performing simulations on industrial robots, mobile robots, and autonomous vehicles (AGV-s) from the safety perspective for humans. A mid-size drone was used for aerial imagery as the first step in creating a virtual environment. Then all the photos were processed in several steps to build the final 3D map. Next, this mapping method was used to create a high detail simulation environment for testing an autonomous shuttle. Developing efficient methods for mapping real environments and simulating their variables is crucial for the testing and development of control algorithms of autonomous vehicles.
Large Eddy Simulations of Francis Turbine Operating at Ultra-Low Loads
Authors: Altimemy Muhannad , Caspar Justin , Watheq Saif , Oztekin Alparslan
Published: February 2021

High-fidelity large eddy simulations (LES) were conducted to characterize the spatial and temporal structure of turbulent flows in an industrial-sized Francis turbine. The unit operated at 50% and 40% of the best efficiency design flowrate. Contours of vorticity, velocity, pressure, and iso-surfaces of Q-Criterion were presented to characterize the effects on the draft tube. Probes placed alongside the draft tube measure the pressure signal to investigate the flow-induced pressure fluctuations inside the turbine unit. The maximum intensity of pressure fluctuations at 50% partial load was 22.66% of the turbine head, while the strength of the pressure fluctuations was 26.36% at 40% partial load. A large number of unorganized smaller vortices observed in the draft tube contribute to the creation of pressure fluctuations. Two pressure modes can be easily recognized (1) high frequency with low amplitude pressure fluctuations and (2) low frequency with high amplitude fluctuations. These pressure fluctuations could be harmful to the structural integrity of the unit and also have undesirable influences on the operational stability of the hydro-turbines.
Machine Learning Using Brain Computer Interface System
Authors: Matsuno Kevin , Nandikolla Vidya K.
Published: February 2021

With commercially available hardware and supporting software, different electrical potential brain waves are measured via a headset with a collection of electrodes. Out of the different types of brain signals, the proposed brain-computer interface (BCI) controller utilizes non-task related signals, i.e. squeezing left/right hand or tapping left/right foot, due to their responsive behavior and general signal feature similarity among patients. In addition, motor imagery related signals, such as imagining left/right foot or hand movement are also examined. The main goal of the paper is to demonstrate the performance of machine learning algorithms based on classification accuracy. The performances are evaluated on BCI dataset of three male subjects to extract the most significant features. Each subject undergoes a 30-minute session composed of four experiments: two non-task related signals and two motor imagery signals. Each experiment records fifteen trials of two classes (i.e. left/right hand movement). The raw data is then pre-processed using a MatLab plugin, EEGLAB, where standard processes of cleaning and epoching the signals is performed. The paper discusses machine learning for robotic application and the common flaws when validating machine learning methods in the context of BCI to provide a brief overview on biologically (using brain waves) controlled devices.
Experimental Investigation of Effects of Graphene Nano Particles (GNP) on the Combustion Behaviors of Renewable Jet Fuel Droplets
Authors: Parveg A. S. M. Sazzad , Singh Gurjap , Ratner Albert
Published: February 2021

Due to the impact of fossil fuel use on the environment, renewable jet fuel has been pursued as an alternative fuel for aircraft engines. Several renewable jet fuels are developed with minimal carbon footprint and pollutants emission to replace petroleum jet fuels. To modify certain combustion behaviors such as combustion rate, ignition delay and total combustion time, colloidal suspension of carbon-based nanoparticles to liquid fuels has proven to be an effective mechanism. But the influence of carbon-based nanoparticles on the combustion behaviors of renewable jet fuels at different concentrations has not yet been investigated. Researchers have been exploring ways to modify the combustion performances of renewable jet fuel, and in this work, the addition of carbon-based nanoparticles (Graphene Nano Particles) is examined as a potential performance enhancing additive for fuel transport safety. The effects of Graphene Nano Particles (GNP) on the ignition and combustion characteristics of soy oil and canola oil based renewable jet fuel at different mass concentrations (1%, 2% & 3%) loading are investigated in this manuscript. The impact of different mass concentrations loading of GNP on the combustion behavior is analyzed by post-processing the high-speed images. It is observed that the ignition delay decreased by 8.52% and combustion rate decreased by 7.26% for renewable jet fuel at 3% GNP loading. GNP also caused a maximum decrease of total combustion time by 13.61% at 3% loading. It is expected that this study will drive further interest in fuel characteristics improvement of renewable jet fuel and will provide experimental data for future computational modeling.
Strength Analysis and Structural Optimization of Multi-Piece Wheels for Heavy Vehicles
Authors: Luo Jintao , Liu Xiandong , Zhang Yue , Shan Yingchun
Published: February 2021

Due to the capacity for high payloads and harsh operating conditions, and the simple demounting tire operation, multipiece wheels are widely used on heavy vehicles and construction machinery. There is potential for weight reduction of one certain multi-piece wheel (type 8.5-20) for heavy vehicles based on its greatly low failure rate from the customer usage data. In order to improve material efficiency, the strength analysis and structural optimization of the multi-piece wheel was systematically studied in this paper. The characteristics of the wheel under the bending load and radial load were simulated by using finite element method (FEM). According to the obtained stress distribution, the rim base was optimized on the basis of its performance under the radial load. SolidWorks, Abaqus and Excel were integrated on the optimization design platform Isight to automate the optimum workflow based on the approximation loop strategy. This strategy packed in Exploration component of Isight is an iterative algorithm which creates an approximation and executes an optimization plan multiple times, updating the approximation automatically between each cycle if deemed necessary. Eventually, the optimal results showed that a good lightweight design effect was acquired, and the weight of the rim base was reduced by 6.5% under requirements of strength and rigidity. The research provides a fast method for the optimal design of wheels because of less calculation of simulation model and fast convergence with above strategy.
Influence of Carotid Artery Stenosis Location on Lesion Progression Using Computational Fluid Dynamics
Authors: Albadawi Muhamed , Abuouf Yasser , Ookawara Shinichi , Ahmed Mahmoud
Published: February 2021

Atherosclerosis is a major arterial disease characterized by the thickening of the arteries’ walls. The development of stenosis at the carotid bifurcation affects the local variations in blood flow dynamic factors. The carotid artery dynamic factors: including the wall shear stress (WSS), time-averaged wall shear stress (TAWSS) and pressure gradient affect the rate of progression of the stenosis. It is essential to analyze the flow in three-dimensional reconstructed patient-specific geometries with realistic boundary conditions to estimate the blood flow dynamic factors. Hence, a three-dimensional comprehensive model is developed including the non-Newtonian blood flow under pulsatile flow conditions. The model is numerically simulated using computational fluid dynamics solvers along with the medical imaging to investigate the effect of stenosis locations on its progression. The numerically predicted blood flow dynamic factors are analyzed. It was found that the blood flow dynamic factors have the importance to influence the diagnosis and prediction of asymptomatic carotid artery stenosis progression. Based on results, the value of TAWSS at the stenosis in the stenotic Common Carotid Artery (CCA) is 46.68 Pa comparing to 19.24 Pa and 10.049 Pa in Internal Carotid Artery (ICA) and External Carotid Artery (ECA) respectively. Also, it was found that the maximum value of WSS in the healthy artery at the bifurcation with 3.829 Pa. However, in stenotic arteries the maximum value for WSS located at the stenosis throat which was found to be 102.158 Pa for CCA comparing to 46.859 Pa in ICA and 33.658 Pa in ECA.