bluuebunny/crossref_metadata_2025 huggingface dataset:
Coronavirus disease 2019 in pregnancy: Case report on maternal death in Sagar City of Central India
Authors: Rawat Sumit K. , Saad Talha , Jindal Ankur , Vyas Ashish K.
Published: February 2021

Background

The infection by SARS‐COV‐2 leading to coronavirus disease has become a worldwide pandemic. It is not clear whether the coronavirus disease (COVID‐19) and its severity differ in pregnant compared to the nonpregnant outcome.

Concerns

Out of four, three pregnant women were discharged with mild symptoms but one pregnant woman admitted at 24 weeks gestation with 3 days of vomiting, breathlessness, and cough had fatal outcome.

Diagnoses

After the medical staff prepared for isolation and protection, the patients quickly underwent with series of diagnostic tests, such as laboratory, imaging, and SARS‐COV‐2 nucleic‐acid examinations.

Outcomes

Among all four SARS CoV‐2 infected pregnant women, three discharged after recovery and delivered healthy babies but one had severe COVID‐19 disease. The women began to exhibit fever, reduced blood oxygen saturation, and despite the interventions, she could not be saved and succumbed to death. There is an early requirement of effective management strategies for pregnant women with COVID‐19.
Photoacclimation State of Thalassiosiraweissflogii is not Affected by Changes in Optical Depth Under A Fluctuating Light Regime Simulating Deep Mixing1
Authors: Brown Matthew , Milligan Allen , Behrenfeld Michael
Published: February 2021

Satellite‐based remote sensing allows for global estimates of phytoplankton primary productivity by converting measurements of ocean color or photon absorption into units of carbon fixation. Models which perform this conversion often require an estimate of phytoplankton photoacclimation state such as the carbon to chlorophyll a ratio (C:Chl). Recently, our group developed a new photoacclimation model that can be applied to models of primary production. The model assumes that the phytoplankton photoacclimation state is not affected by periods of darkness during deep mixing beneath the photic zone, due to reduction in the plastoquinone pool in darkness and the subsequent deactivation of the signal for chlorophyll synthesis. In this study, we tested these assumptions by culturing the marine diatom Thalassiosira weissflogii under fluctuating light conditions simulating three different optical depths with progressively increasing deep mixing periods. The photoacclimation state, measured by the ratio of C:Chl, in T. weissflogii was not affected by changes in the length of simulated deep mixing periods. In addition, analysis of photosynthesis vs. irradiance (PE) curves showed that increases in optical depth caused decreases in both the maximum Chl‐normalized rate of photosynthesis (Pbmax) and in the slope of light‐limited photosynthesis (αb), but had no effect on the half‐saturation irradiance (Ek, another metric of photoacclimation). However, measurements of chlorophyll fluorescence during simulated deep mixing did not support the hypothesis that the PQ pool was reduced during dark periods. Thus, our findings support the use of the photoacclimation model for estimating primary production while suggesting the need for further research into the mechanisms controlling photoacclimation in the upper mixed layer environment of the ocean.
Glecaprevir/pibrentasvir is safe and effective in hepatitis C patients with cirrhosis: Real‐world data from the German Hepatitis C‐Registry
Authors: Wedemeyer Heiner , Erren Peter , Naumann Uwe , Rieke Ansgar , Stoehr Albrecht , Zimmermann Tim , Lohmann Kristina , König Bettina , Mauss Stefan
Published: February 2021

Glecaprevir/pibrentasvir is a pangenotypic direct‐acting antiviral regimen approved for treating chronic hepatitis C virus. Real‐world use of protease‐inhibitor–containing regimens requires further evaluation in patients with cirrhosis. We evaluated the real‐world safety and effectiveness of glecaprevir/pibrentasvir in patients with cirrhosis from the German Hepatitis C‐Registry who initiated treatment between 2 August 2017‐30 June 2019. Overall, 131 patients received on‐label treatment. No patient discontinued treatment due to adverse events. Four patients had serious adverse events; none were considered related to glecaprevir/pibrentasvir. Two patients had total bilirubin >5 × upper limit of normal (ULN) during treatment. Three patients had alanine aminotransferase and three patients had aspartate aminotransferase >3 × ULN. Rates of sustained virologic response were 100% (86/86) for 86 patients with available data. A total of 51 patients received off‐label treatment, of which 3 had a serious adverse event. Glecaprevir/pibrentasvir treatment was well‐tolerated and highly effective in patients with chronic hepatitis C and cirrhosis in real‐world practice.
YtkA (CtaK) and YozB (CtaM) function in the biogenesis of cytochrome c oxidase in Bacillus subtilis
Authors: von Wachenfeldt Claes , Hallgren Joel , Hederstedt Lars
Published: February 2021

Cytochrome c oxidase in the respiratory chain of bacteria and mitochondria couples the reduction of molecular oxygen to form water with the generation of a transmembrane proton gradient. Bacillus subtilis has two heme A‐containing heme–copper oxidases: the menaquinol oxidase cytochrome aa3 and the cytochrome c oxidase cytochrome caa3. By screening three collections of mutants for defective cytochrome c oxidase, we found the genes for two, new membrane‐bound assembly factors in B. subtilis: ytkA and yozB (renamed ctaK and ctaM, respectively). CtaK is a lipoprotein without sequence similarity to any protein of known function. We show that CtaK functions together with Sco1 (YpmQ) in a pathway, leading to the assembly of the CuA center in cytochrome caa3 and seems to be a functional analogue to proteins of the periplasmic CuA chaperone family (PCuAC). CtaM is required for the activity of both cytochrome caa3 and cytochrome aa3 and dispensable for the insertion of heme A into these oxidases. The orthologous Bacillus anthracis protein and the distantly related Staphylococcus aureus CtaM complemented CtaM deficiency in B. subtilis, establishing a common function of CtaM in these bacteria. As the overall result of our work, 12 different proteins are known to function in the biosynthesis of cytochrome c oxidase in B. subtilis.
A single system detects and protects the beneficial oral bacterium Streptococcus sp. A12 from a spectrum of antimicrobial peptides
Authors: Lee Kyulim , Kaspar Justin R. , Rojas‐Carreño Gisela , Walker Alejandro R. , Burne Robert A.
Published: February 2021

The commensal bacterium Streptococcus sp. A12 has multiple properties that may promote the stability of health‐associated oral biofilms, including overt antagonism of the dental caries pathogen Streptococcus mutans. A LanFEG‐type ABC transporter, PcfFEG, confers tolerance to the lantibiotic nisin and enhances the ability of A12 to compete against S. mutans. Here, we investigated the regulation of pcfFEG and adjacent genes for a two‐component system, pcfRK, to better understand antimicrobial peptide resistance by A12. Induction of pcfFEG‐pcfRK was the primary mechanism to respond rapidly to nisin. In addition to nisin, PcfFEG conferred tolerance by A12 to a spectrum of lantibiotic and non‐lantibiotic antimicrobial peptides produced by a diverse collection of S. mutans isolates. Loss of PcfFEG resulted in the altered spatio‐temporal arrangement of A12 and S. mutans in a dual‐species biofilm model. Deletion of PcfFEG or PcfK resulted in constitutive activation of pcfFEG and expression of pcfFEG was inhibited by small peptides in the pcfK mutant. Transcriptional profiling of pcfR or pcfK mutants combined with functional genomics revealed peculiarities in PcfK function and a novel panel of genes responsive to nisin. Collectively, the results provide fundamental insights that strengthen the foundation for the design of microbial‐based therapeutics to control oral infectious diseases.
Accommodating Embodied Thinkers
Authors: Tanton Tobias
Published: February 2021

The principle of divine accommodation posits that revelation is accommodated to human cognitive capacities. It is regularly cited throughout the history of theology as an exegetical tool, as a doctrinal rationale, or as a condition for theological knowledge in general. This article proposes that divine accommodation invites an engagement with cognitive science, since findings in cognitive science illuminate the human cognitive capacities to which theological knowledge is accommodated. This article aims to demonstrate the fruitfulness of such an engagement by considering how theological concepts might be accommodated to accounts of human conceptualisation emerging from cognitive science. In particular, a case study considers the ‘conceptualisation hypothesis’ from ‘embodied cognition’, an emerging paradigm in cognitive science. This hypothesis suggests that human concepts are ‘grounded’ in sensorimotor states. If this scientifically‐motivated theory applies to all human concepts, it poses a potential theological dilemma: namely, if God‐concepts are grounded in sensorimotor states they prima facie risk being idolatrous, whereas if they are not so grounded, they may be un‐conceptualisable by humans. I suggest that one way to address this dilemma is to draw upon Athanasius’ insight that the incarnation plays a crucial role in accommodating human understanding. By examining the incarnation as an accommodation to human capacities uncovered by cognitive scientists, we gain a more comprehensive account of the epistemological reason for the incarnation. This account offers new lines of thinking about debates on the doctrine of the incarnation, such as the possibility of multiple incarnations.
Outcomes of cardiac resynchronization therapy in patients with chemotherapy‐induced cardiomyopathy
Authors: Ezzeddine Fatima M. , Saliba Antoine N. , Jain Vaibhav , Villarraga Hector R. , Herrmann Joerg , Asirvatham Samuel J. , Cha Yong‐Mei
Published: February 2021

Background

Several chemotherapy agents are associated with the development of non‐ischemic cardiomyopathy (NIC). When chemotherapy‐induced cardiomyopathy (CHIC) is associated with left bundle branch block (LBBB) and a left ventricular ejection fraction (LVEF) 35% or lower, cardiac resynchronization therapy (CRT) is often utilized to improve cardiac function and relieve symptoms.

Objective

To determine the echocardiographic and clinical outcomes of CRT in patients with CHIC.

Methods

The study included 29 patients with CHIC (CHIC group) and 58 patients with other types of NIC (control group) who underwent CRT implantation between 2004 and 2017. The primary endpoints were changes in LVEF, left ventricular end‐systolic diameter (LVESD), and left ventricular end‐diastolic diameter (LVEDD) at 6–18 months after CRT. The secondary outcomes included changes in left ventricular global longitudinal strain (GLS), systolic strain rate (SRS), early diastolic strain rate (SRE), and overall survival.

Results

Out of 29 patients with CHIC, 62.1% received chemotherapy for lymphoma, 13.7% for breast cancer, and 24.1% for sarcoma. The agent implicated in 93.1% of the patients was an anthracycline. Half of the patients had LBBB. The mean baseline LVEF was 28% ± 8%. The mean baseline QRS duration was 146 ± 26 ms. Twenty‐eight patients had post‐CRT follow‐up data. CRT was associated with improvement in echocardiographic outcomes in the CHIC group and the control group. There was no difference in overall survival between the two groups (log‐rank p = .148).

Conclusion

CRT improves left ventricular function and reverses remodeling in patients with CHIC.
Impact of High Solar UV Radiant Exposures in Spring 2020 on SARS‐CoV‐2 Viral Inactivation in the UK†
Authors: Rendell Rebecca , Khazova Marina , Higlett Michael , O’Hagan John
Published: February 2021

Potential for SARS‐CoV‐2 viral inactivation by solar UV radiation in outdoor spaces in the UK has been assessed. Average erythema effective and UV‐A daily radiant exposures per month were higher (statistically significant, P < 0.05) in spring 2020 in comparison with spring 2015–2019 across most of the UK, while irradiance generally appeared to be in the normal expected range of 2015–2019. It was found that these higher radiant exposures may have increased the potential for SARS‐CoV‐2 viral inactivation outdoors in April and May 2020. Assessment of the 6‐year period 2015–2020 in the UK found that for 50–60% of the year, that is most of October to March, solar UV is unlikely to have a significant (at least 90% inactivation) impact on viral inactivation outdoors. Minimum times to reach 90% and 99% inactivation in the UK are of the order of tens of minutes and of the order of hours, respectively. However, these times are best case scenarios and should be treated with caution.
The Role of Slip and No Slip Behavior on Droplet Impingement
Authors: Pati A. R. , Swain B. , Mohapatra S. S.
Published: February 2021

For the identification of role of slip and no slip conditions at the solid–liquid interface in case of hydrophobic, superhydrophilic, and superhydrophobic surfaces, the experimentally determined velocity profiles are analyzed. Before experimentation, each surface was characterized by using scanning electron microscope (SEM), two-dimensional, and three-dimensional surface profilometer. The impact mapping results reveal that in case of hydrophobic surface, first no slip condition is achieved and then slip condition is noticed. Conversely, for superhydrophilic surface, initially slip and then no slip conditions are observed. Furthermore, in case of superhydrophobic surface, slip behavior is observed throughout the process for the dimensionless time ranges 0.06–0.94 and this behavior of the process promotes local enhancement of viscous and capillary forces. The experimentally obtained results are further tried to validate with the help of theoretical and visual observations.
Flaw Evaluation Procedure for Cast Austenitic Stainless-Steel Materials Using a Newly Developed Statistical Thermal Aging Model
Authors: Uddin Mohammed , Sallaberry Cédric , Wilkowski Gery
Published: February 2021

Thermal embrittlement of some cast austenitic stainless steels (CASS) occurs at reactor operating temperatures leading to very low fracture toughness. Because of their low aged toughness with high variability, flaw evaluations of CASS material need to be established with an understanding of the materials aged condition, especially since most U.S. pressurized water reactor (PWR) nuclear plants have been given plant life extensions for 60-year operation. A flaw evaluation procedure for CASS materials is presented here using a new statistical model developed to predict the toughness of fully aged CASS using the materials' chemical compositions. In this procedure, the dimensionless-plastic-zone-parameter (DPZP) analysis is used to determine when limit-load is applicable and also approximate the elastic-plastic correction factor (Z-factor) to predict the failure stress for CASS pipe/fittings with a circumferential surface crack. The procedure was validated against several CF8m pipe test results which include various pipe diameters, crack sizes, ferrite contents, failure modes. The as-developed flaw evaluation procedure was also used to determine the Z-factors for four different pipe diameters for a database of 274 pipe/elbows in U.S. PWR plants –solving 1096 sample problems to understand what range of Z-factors in U.S. PWR plants (for CF8m CASS materials). Finally, the applicability of the CF8m-based statistical model for use with CF3 and CF8 CASS materials was also verified with available test results. The outcome of this work has been implemented in an ASME boiler and pressure vessel (BPV) code case and has been approved in 2020 as Code Case N-906.
Numerical Investigation of Rayleigh–Benard Natural Convection and Entropy Generation in a Cubic Cavity With Discrete Heat Sources
Authors: Maatki Chemseddine , Ghachem Kaouther , Almeshaal Mohammed A. , Ben Khedher Nidhal , Kolsi Lioua
Published: February 2021

Three-dimensional (3D) natural convection with isothermal discrete heat sources in a cubical cavity has been carefully studied using the 3D vector potential–vorticity formulation. Based on the finite volume method, the governing equations are solved with a homemade computational code (written in Fortran). Assuming that all cavity vertical walls are adiabatic, the upper wall of the cavity is kept at a cold temperature. However, in the bottom face, heat sources are placed under different configurations. The size of the discrete sources, their positions, and their numbers are varied for different Rayleigh numbers. The Prandtl number is fixed at 0.71. Three-dimensional distribution of the temperature iso-surfaces, the heat transfer rate, and entropy generation is evaluated. It is found that heat transfer and entropy generation are strongly affected by the arrangement of the discrete heated sources. In conclusion, the heat transfer rate is maximized, and the entropy generation is minimized for the inline arrangement of more than two heaters compared to the diagonal one.
Pressure Loss Coefficients for VAV Terminal Units
Authors: Lankalapalli Kiran , Idem Stephen
Published: February 2021

This study utilizes static pressure drop data taken from one manufacturer’s catalog to develop total pressure loss coefficient correlations for single duct VAV terminal units having a circular inlet duct and a rectangular outlet. The control dampers for each box were assumed to be in their wide open position. Separate correlations are presented for cases including a plain box, as well as terminal units that have either hot water reheat coils consisting of one to four tube rows, or an electrical heating element. In every instance the correlations account for static pressure and velocity pressure changes between the box inlet and outlet, based on cross section changes. The correlations are useful for duct designers, since they facilitate the utilization of numerical duct design approaches that require extensive iterative calculations, such as the static regain method. The correlations are proposed for inclusion in duct fitting loss coefficient databases.
Design of a Mechanical Sealing Device for Robotic Water Distribution Pipe Rehabilitation
Authors: Yeung Yip Fun , Genevriere Emily , Youcef-Toumi Kamal
Published: February 2021

Water distribution pipe maintenance is a global concern. In this study, we propose a Rehabilitation In-Pipe Robot (R-IPR) to perform pipe rehabilitation operations and contain induced contamination. The robot features three modules: a pipe cleaning module, a mechanical sealing module, and an in-pipe manipulator module. This study emphasizes the comprehensive design of the mechanical sealing module. We introduce a multi-layer compound structure of the seal to deal with two characteristics of tuberculated pipe surfaces: 1. macroscopical surface roughness, 2. overhang in foundation profile. The prototype excels in sealing foundation overhang and requires 45% lower compression load than a baseline seal to function. The prototype seal is integrated into the R-IPR. Finally, experiments of the overall system demonstrate the successful performance of the first contamination-less in-pipe rehabilitation.
Effect of Strain Rate on Tensile Properties of Injection Molded Multiwall Carbon Nanotube Reinforced PA 6/6 Nanocomposites
Authors: Reza Sanei Seyed Hamid , Drozynski Hanna , Hetrick Dakota
Published: February 2021

The mechanical properties of polymers highly depend on the loading rate, however, the effect of loading/strain rate with the addition of Carbon Nanotube is not well understood. In this study, the effect of Carbon Nanotube (CNT) content on the rate dependence of polymers was studied. Injection molded mini-tensile samples with CNT content ranging from 0 to 15wt% at strain rates of .0006, .0013, .0019 and .0025 s−1 were tested. It was found that as strain rate increased, the ultimate strength and Young s Modulus of the tensile specimens increased. It was also shown that addition of CNT will lower the chain mobility of polymer and lower the polymer dependence of properties to strain rates.
Transient Vibration and Feedback Control of an Inductrack Maglev System
Authors: Wang Ruiyang , Yang Bingen , Gao Hao
Published: February 2021

As a new strategy for magnetic levitation envisioned in 1990s, the Inductrack system with permanent magnets (PMs) aligned in Halbach arrays has been intensively studied and applied in many projects. Due to the nonlinear, time-varying electro-magneto-mechanical coupling in such a system, the dynamic behaviors are complicated with transient responses, which in most cases can hardly be predicted with fidelity by a steady-state Inductrack model. Presented in this paper is a benchmark 2-DOF transient Inductrack model, which is derived from the first laws of nature, without any assumed steady-state quantities. It is shown that the dynamic response of the Inductrack dynamic system is governed by a set of nonlinear integro-differential equations. As demonstrated in numerical simulations with the transient model, unstable vibrations in the levitation direction occur when the traveling speed of the vehicle exceeds a threshold. To resolve this instability issue, feedback control is implemented in the Inductrack system.

In the development, an assembly of Halbach arrays and active coils that are wound on the PMs is proposed to achieve a controllable source magnetic field. In this preliminary investigation, the proposed control system design process takes two main steps. First, a PID controller is set and tuned based on a simple lumped-mass dynamic system. Second, the nonlinear force-current correlation is obtained from a lookup table that is pre-calculated by steady-state truncation of the full transient Inductrack model. With the implemented feedback control algorithms, numerical examples display that the motion of the vehicle in levitation direction can be effectively stabilized at different traveling speeds. Although only a 2-DOF transient model is used here, the modeling technique and the controller design approach developed in this work are potentially applicable to more complicated models of Inductrack Maglev systems.
Use of A3 Report by Industrial Engineering Students As a Tool to Analyze and Interpret a Case Study
Authors: Alves Anabela C.
Published: February 2021

Lean Thinking is a philosophy which principles were redesigned from Toyota Production System (TPS) by Womack and Jones of MIT. Currently, Lean Thinking principles are taught in the academy and are applied in all sectors, from production to services. Services is what is provided to students in a university. Teachers provide a service to them, and they are the clients of this service. As so, teachers want to provide the best service, adding value to the “client” product. In order to do so, they search for new methods that create flow in the way students learn what they need to learn. Lean Thinking have been providing tools to the classroom to obtain such flow. This paper intends to present a tool, an A3 report, which was used by engineering students to analyze, interpret and report a published case study. This was a team assignment task among others. This task was assessed as a component for the final grade of a course of third year of Master Integrated of Industrial Engineering and Management (IEM). The presentations, A3 reports and discussions results were analyzed and compared using Bloom taxonomy levels and 3H taxonomy to infer about students learning. Main findings obtained were very positive.
New ABET Student Outcomes Assessment: Developing Performance Indicators and Instruments for Outcome 4
Authors: Kumpaty Subha , Reichl Katie , Vyas Anand
Published: February 2021

Milwaukee School of Engineering’s Mechanical Engineering Department, having successfully completed the accreditation of the ME program in 2018–19 under the prior a through k student outcomes, dedicated the program meetings during academic year 2019–20 to develop assessment instruments in transitioning to the new ABET Student Outcomes 1–7. By deliberately involving the entire faculty to participate in the development of instruments, a grassroots level discussion and creation ensued for each outcome. The process is showcased in this paper for Student Outcome 4 on ethics as a model to share with our engineering faculty and to highlight salient features in the developed instrument and associated rubrics. The details of performance indicators interwoven across the curriculum and the methods of data collection are provided in a tabular form for ease of expectation and implementation. How the readily available materials from the National Society of Professional Engineers could be incorporated at early years of the baccalaureate program while the outcome’s performance indicators could be assessed at a deeper level during junior and senior years are showcased in this paper. The periodic dialogue among all colleagues who were working on various outcomes ensured proper communication of what one outcome group is prescribing that we do and receive input from those who are involved with the courses in which the data needed to be collected and the performance indicators are to be assessed. The general structure of our standing committees on freshman courses, energy, mechanics, and controls also provided the cushion to review the assessment instruments and provide constructive feedback from the corresponding committee’s perspective. These details of a very interactive Student Outcomes Assessment process will be presented.
Effect of Interfacial Contact Forces and Lay Ratio in Cardiac Lead Outer Insulation due to Internal Cable Motion
Authors: Gnanavel B. K. , Raja G. , Chandramohan D.
Published: February 2021

Wearing cardiac lead implanted may result in various failures, including in-appropriate or missing treatments. Contacts are used on the lateral and radial link in the multi-layered (1 + 6 + 12) pacemaker lead cable. The effect of the coupling mode, however, is not the same as it does when the lateral and radial contact combine. On the transverse wire the forces and moments developed along the regular, bi-natural, and axial directions on a helical wire of the multi-faceted pacemaker cable. The equilibrium equations derived from Love’s thin rod theory (1944) shall provide geometric nomenclatures of the cabling generated by axial stress and rotational pressures from the multi-layered pacemaker lead. A steepness matrix is derived for multi-layered pacemakers leading cable elements, leading to strand strength, a twisting moment, axial strand strain and rotational strain.
Design of 1-DOF Robot With Humanoid Gait for Lower Limb Rehabilitation Based on Watt-I Six-Bar Mechanism
Authors: Song Wanbing , Gu Chenchen , Hou Qitao , Teng Zhiqiang , Zhao Ping
Published: February 2021

The major drawbacks of current lower limb rehabilitation robots are high cost and complex structure which make them inappropriate to be applied in the community and family. In this paper, we design an 1-degree-of-freedom (DOF) robot with humanoid gait for lower limb rehabilitation based on Watt-I six-bar mechanism. Let the normal gait trajectory be target trajectory, the dimensions of the mechanism are calculated by path synthesis. First, the objective function to reflect the accuracy of trajectory reproduction and relevant constraints are established. Then GA-BFGS hybrid algorithm is used to minimize the objective function. After that, the optimized mechanism is analyzed by trajectory comparison, velocity / acceleration analysis and joint angle detection. Further, the kinematic simulation of the mechanism is also completed. The results show that while the crank is rotating at a constant speed, the mechanism can reproduce the time sequence and the shape of target trajectory approximately to realize walk training for patients with lower limb disorders whose legs are 810.0–860.0mm long (the corresponding heights are about 1650.0–1750.0mm). Finally, the specific structure of lower limb rehabilitation robot based on this mechanism is designed and the principle prototype model is given.
Two-Dimensional WS2/g-C3N4 Layered Heterostructures With Enhanced Pseudocapacitive and Electrocatalytic Properties
Authors: Ola Oluwafunmilola , Zhu Yanqiu
Published: February 2021

In this work, tungsten-based hybrid nanocomposites were grown on interconnected, macroscopic graphitic carbon nitride scaffold after solvothermal treatment followed by sulfidation to attain multifunctional composite electrocatalysts. The physicochemical properties of the obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The tungsten-based composites were tested as electrodes for pseudocapacitors and as electrocatalysts for hydrogen evolution reaction, to take advantage of their porous graphitic carbon nitride features which would be beneficial for optimal ion transport to tungsten-based nanoparticles. These unique physicochemical features endow these composites with excellent electrochemical performances to reach a current density of 10 mA/cm2 for the hydrogen evolution reaction. In addition to demonstrating excellent specific capacitance, these hybrid nanocomposites also possess good stability after 8 hours of testing.
Development of a 3D Printed Soft Parallel Robot
Authors: Garcia Martin , Moghadam Amir Ali Amiri , Tekes Ayse , Emert Randy
Published: February 2021

This paper reports on design, fabrication, and kinematics modeling of a 3D printed soft parallel robot equipped with soft pneumatic actuators. Soft robotics is an emerging field of research which facilitates safe human machine interface. Soft elastomeric actuators made through molding process are one of the key elements of soft robotic systems. However, molding process is tedious and time consuming making the fabrication process undesirable. Recently reported 3D printed soft pneumatic actuators pave the way for manufacturing of novel soft actuators and robots with complex geometries. The current work can be considered as a proof of concept for 3D printing of a soft parallel robot. The robot consists of two soft pneumatic actuators that are connected to two passive links by mean of flexible hinges. The robot has two degrees of freedom and can be used in planar manipulation tasks. Moreover, a number of robots can be configured to operate in a cooperative manner to increase the manipulation dexterity. A kinematic model is developed to simulate the motion of robot end-effector. Through application of the kinematic model it has been shown that the robot is capable of following any planar trajectories within its workspace. Also, pseudo-rigid-body model (PRBM) is used to develop a dynamic model of the soft robot to more accurately predict the robot interaction with its environment and also develop advanced control system for robust position control of the robot.
Embedded 3D Printing of Highly Flexible Nanocomposites With Piezoresistive Sensing Capabilities
Authors: Herren Blake , Saha Mrinal C. , Altan M. Cengiz , Liu Yingtao
Published: February 2021

In recent years, highly flexible nanocomposite sensors have been developed for the detection of a variety of human body movements. To precisely detect the bending motions of human joints, the sensors must be able to conform well with the human skin and produce signals that effectively describe the amount of deformation applied to the material during bending. In this paper, a carbon nanotube-based piezoresistive strain sensor is developed via the direct ink writing based embedded 3D printing method. The optimum weight concentration range of carbon nanotubes in the nanocomposite inks, appropriate for embedded 3D printing, is identified. Samples with complex 2D and 3D geometries are printed to demonstrate the manufacturing capabilities of the embedded printing process. The sensitivity of the piezoresistive strain sensor is optimized by determining the ideal nanofiller concentration, curing temperature, and nozzle size to produce the highest gauge factor in a wide strain range. The piezoresistive and mechanical properties of the optimized sensors are fully characterized to verify the suitability for skin-attachable strain sensing applications. The developed sensors have a wide sensing range, high sensitivity, and minimal strain rate dependence. In addition, their low elasticity and high biocompatibility allow them to be comfortably bonded on the human skin.
Experimental and Analytical Study for Condenser Shading Effects on Air-Conditioning System Performance
Authors: Shehadi Maher
Published: February 2021

An experimental and analytical study for performance of shaded condensers is presented. A three tons of refrigeration (TR) unit installed in a 2-story house was experimentally studied between June and September. Analytical simulations for a 3 TR unit and for a wider range of capacities ranging from 80 to 370 TR was done. The experimental results for the 3 TR unit showed 12–39% improvement in the COP of the cycle under various evaporator temperatures with uncertainty levels between ±1.63–13.6%. The simulated results for the same capacity (3 TR) showed higher improvements than the experimental ones. However, for larger capacities, the simulations showed lower improvements than the 3 TR unit and ranged between 10–14%.
Vision-Based SLAM Robot Spider: An Undergraduate Project of Advanced Robotics of Bachelor of Technology
Authors: Beckwith Caleb , Zhang Shaojin , Esche Sven K. , Zhang Zhou
Published: February 2021

Bachelor of Technology (B.Tech) of robotics is a skill-oriented degree, and the students are usually not well-prepared both in theoretical knowledge and the opportunities to reach cutting-edge technologies. To overcome the above two difficulties, some challengeable projects are designed as the undergraduate projects of B.Tech of robotics. Among them, a SLAM robot spider is implemented. This project employed robotics vision, PID control, dynamics, kinematics, and additive manufacturing. Its structure is fabricated through additive manufacturing. The skeleton is composed of three main parts: six legs, torso, and head. Each leg has three joints which are driven by servo motors. The torso is used to mount the sensors, control modules, communication modules, and power source. The ‘NVIDIA Jetson Nano’ is used to control the motors, manage the communication interfaces, and process the sensing data. The ‘Intel RealSense depth camera’ and ’Intel RealSense tracking camera’ are used to futile the task of SLAM. The depth camera is used to acquire depth data to generate 3D point clouds. The tracking camera is an auxiliary reference to help to steer and to locate the position. Besides, an iPad tablet is used to provide a manual control option and render the scene in real-time.
Soft-Body Simulation With CUDA Based on Mass-Spring Model and Verlet Integration Scheme
Authors: Zhang Zhou
Published: February 2021

Soft-body simulation is widely used in animation, prostheses, organs, and so on. The most common way is to use 3D software. However, Their simulation models and the data processing speed are limited. Therefore, one model based on the mass-spring mechanism is proposed. To realize real-time rendering, a parallel computing architecture based on the CUDA architecture is introduced. Besides, to increase the accuracy of the simulation, the Verlet integration is employed. The work is to check whether the massively parallel computing method based on the CUDA architecture improves the rendering performance. To meet the minimum requirement to make the human eye comfortable, all the tests had at least a 60 Hz refreshing rate. Also, the soft body of mass-particles and springs has a uniform width and depth, but the height is much smaller. It was modeled to fall under the influence of gravity, and then, to impact on a rigid object. The serial and the parallel methods were not significantly different when the rendering nodes were less than 2,000, but it became apparent when the number of nodes reached 10,000. Therefore, the simulation efficiency of a soft body is improved by the proposed method.
Numerical Analysis of Fluid Flow in 2D Domains Containing Moving Objects
Authors: Mazumder A. K. M. Monayem H.
Published: February 2021

This study presented a two-dimensional (2D) numerical analysis of fluid flow in domains containing moving objects. The method falls into the general category of Arbitrary-Lagrangian-Eulerian (ALE) methods, which is based on a fixed mesh that is locally fitted at the moving objects. The moving objects are described using sets of marker points which can slide over the basic mesh. Once the moving object has gone through the stationary element, the element is restored to its original form. Therefore, the mesh adaptation is performed only in those elements intersected by an object and is local both in space and time. As a result, the method does not require interpolation and there are a fixed number of possible modifications to the intersected elements. As the global mesh is independent of object movement, therefore it eliminates the possibility of mesh entanglement. The mesh never becomes unsuitable due to its continuous deformation, thus eliminating the need for repeated re-meshing and interpolation. A validation is presented via a problem with an exact analytical solution to the case of 2D flow between two parallel plates separating with a prescribed velocity. The method’s capabilities and accuracy are illustrated through application in realistic geometrical settings which show the robustness and flexibility of the technique.
Law of Metal Flow of Thin-Walled Conical Part With Variable Section During Spinning
Authors: Xuedao Shu , Yingxiang Xia , Ying Zhu , Zixuan Li , Bohai Ye
Published: February 2021

During the spinning process of the variable-section thin-walled conical parts, the metal flow law is relatively complicated and the flange is prone to be unstable, which resulting in wrinkling and other defects. In this paper, the variable-section conical part of superalloy GH1140 is taken as the research object. The spinning forming process is numerically simulated by using Simufact Finite Element software and the metal flow in each stage of the forming process is analyzed. The flow velocity shows an annular distribution as a whole. The metal near the center of the circle flows more slowly, and the metal far from the circular flange flows more quickly. In the direction of thickness, the velocity of metal flow decreases gradually. Under the feeding action of the roller, the metal in front of the roller is subjected to axial tensile stress, tangential and radial compressive stress, resulting in a strain state of one-way tension and two-way compression. The metal moves along the negative direction of the rotary wheel feed, resulting in the increase of the sheet wall thickness. The correctness of the model in this paper is further verified by spinning experiments. The research results provide a theoretical basis for analyzing the mechanism of forming defects and improving the quality of spinning forming of conical thin-walled parts with variable sections.
Formalizing Performance Evaluation of Mobile Manipulator Robots Using CTML
Authors: Aboul-Enein Omar , Jing Yaping , Bostelman Roger
Published: February 2021

Computation Tree Measurement Language (CTML) is a newly developed formal language that offers simultaneous model verification and performance evaluation measures. While the theory behind CTML has been established, the language has yet to be tested on a practical example. In this work, we wish to demonstrate the utility of CTML when applied to a real-world application based in manufacturing. Mobile manipulators may enable more flexible, dynamic workflows within industry. Therefore, an artifact-based performance measurement test method for mobile manipulator robots developed at the National Institute of Standards and Technology was selected for evaluation. Contributions of this work include the modeling of robot tasks implemented for the performance measurement test using Petri nets, as well as the formulation and execution of sample queries using CTML. To compare the numerical results, query support, ease of implementation, and empirical runtime of CTML to other temporal logics in such applications, the queries were re-formulated and evaluated using the PRISM Model Checker. Finally, a discussion is included that considers future extensions of this work, relative to other existing research, that could potentially enable the integration of CTML with Systems Modeling Language (SysML) and Product Life-cycle Management (PLM) software solutions.
Applications of Solar Powered Cooling System Using Integrated Variable Effect Absorption Chillers With Ice Thermal Energy Storage in UAE
Authors: Siddiqui Taabish , Ghaith Fadi
Published: February 2021

This paper addresses the potential of integrating parabolic trough collector (PTC) with variable effect absorption chiller assisted with ice thermal energy storage (ITES) for the purpose of space cooling in residential buildings. In this work, the thermal performance of the proposed integrated system was evaluated in order to assess the system’s capability to fulfil the cooling demands. The proposed system was modelled numerically and simulations were performed using TRNSYS software. Initially during the day, the chiller was operated in a single stage mode to provide required direct cooling to the building. Once the thermal output of the PTC is adequate, a double-effect absorption cooling was activated, with the production of sub-zero evaporator temperatures in order to charge the ice storage prior to providing chilled water to the load during night time. The obtained results showed that the proposed system is capable to provide a continuous space cooling for 20 hours from which 11 hours of cooling were generated using the absorption chiller, whilst the ice storage acts as a backup source of cooling for additional 9 hours during nighttime. For the remainder of the time of almost 4 hours, a biomass auxiliary heater was used to activate the chiller during startup period thus eliminating completely the need of a conventional cooling system. The performed cost analysis proved the feasibility of the proposed system with pay-back period of 3.5 years.
Layered Image Collection for Real-Time Defective Inspection in Additive Manufacturing
Authors: Song Jinwoo , Bandaru Harika , He Xinyu , Qiu Zhenyang , Moon Young B.
Published: February 2021

In Additive Manufacturing (AM), detecting cyber-attacks on infill structure is difficult because interior defects can occur without affecting the exterior. To detect the infill defectives quickly, layer-by-layer image inspection in real-time can be conducted. However, collecting the layered images from the top view in real-time is challenging because the 3D printer’s extruder interferes with objects from being perfectly scanned. Using a dummy model to move the extruder out of the object’s layer has been proposed. However, it is not practical because it creates printing delays and wasted printing materials.

To enable infill layered image collection in real-time without delays and material waste, this research proposes a layered image collection method using an algorithm identifying a pseudo area in a layered image. The algorithm detects the pseudo area — the area covered by the extruder — using an image processing technique, such as an average pooling and max pooling. It accumulates the non-pseudo areas until a complete layered image is acquired. To validate and evaluate the proposed method, captured images were evaluated with various machine learning algorithms.
URANS Modeling of Effects of Rotation on Flow Distribution and Heat Transfer in an Electric Motor
Authors: Tiwari Ankit , Yavuzkurt Savas
Published: February 2021

Traction motors are electric motors used in vehicle propulsion. In this study, an externally cooled 3-phase AC induction motor which has cooling tubes drilled axially throughout the length of the rotor and stator, is analyzed for thermal performance. The cooling air is supplied by a centrifugal blower connected to the inlet plenum of the motor. Unlike in static condition, the relative distribution of air in the rotor and the stator tubes is not uniform and varies due to the rotation of rotor. It has been shown in previous studies that due to rotor’s rotation, the resistance of the flow path through the rotor tubes increases compared to the static condition. This results in reduction of flow through the rotor tubes. Generally, the steady state MRF (Multiple Reference Frame) approach is used to model the rotational effect. While this approach works in the initial design phase, Unsteady sliding mesh approach is suggested for design validation. It was found that at 3000 RPM, the mass flow rate in the rotor predicted by the Sliding mesh model could be as much as 16% lower than that predicted by the MRF model. To assess its impact on thermal performance, steady state conjugate heat transfer analysis was performed. It was found that the rotor temperatures could be up to 8.6-degree C higher based on the mass flow predictions by sliding mesh approach compared to the MRF approach.
A Numerical Study of Forced Convection Casson Nanofluid Flow Past a Wedge With Melting Process
Authors: Endalew Mehari Fentahun , Sarkar Subharthi
Published: February 2021

A numerical investigation is carried out to analyze steady two dimensional Casson nanofluid flow past a wedge with melting. The partial differential equations that govern the nanofluid flow are transformed into highly nonlinear coupled ordinary differential equations by employing similarity transformation. Thereafter, numerical solutions of these governing equations are obtained by MATLAB routine bvp4c. A special case of the present study is compared with an existing solution in literature and is found to be in good agreement. The effects of pertinent physical entities on the nanofluid velocity, nanofluid temperature, and nanoparticle concentration are represented graphically, while skin friction, Nusselt number, and Sherwood number are recorded in tabular form. We observed that, with an increase of wedge angle parameter, nanofluid velocity and local skin friction increase. However, when the melting parameter increases, nanofluid temperature and heat transfer rate decrease. This study would be useful in unfurling novel applications of Casson nanofluids in cooling devices and heat sinks.
Research on Dynamic Characteristics of the High-Speed Cable Force Transmission
Authors: Hou Senhao , Tang Xiaoqiang , Wang Yuheng , Wang Dianjun
Published: February 2021

During the landing and detection missions of the Moon, Mars, and asteroids, due to the complexity and unpredictability of the landing process, it is necessary and critical to carry out simulation tests on the ground to simulate the stress state during the separation of the backshell from the lander. A high-speed cable-driven mechanism adopted. The cable force is different at the end actuator and the drum. There are many factors causing this difference, such as high acceleration, cable stiffness, cable density, cable length. In this paper, the cable force transmission of spacecraft during high-speed separation is studied. The dynamic model of high-speed cable-driven mechanism is established based on Newton principle, then the trial function is introduced, and the second-order partial differential equation is solved by using the method of space discretization. The force relationship of the cable in the process of motion is obtained, and the influencing factors of the cable force are explored. Finally, the correctness of the research content in this paper is verified by numerical simulation and experiment. The results show that the model can accurately simulate the force state of the cable, and it has guiding significance for the active high-speed separation test of spacecraft.