bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protective roles for myeloid cells in neuroinflammation
Authors: Owens Trevor , Benmamar‐Badel Anouk , Wlodarczyk Agnieszka , Marczynska Joanna , Mørch Marlene T. , Dubik Magdalena , Arengoth Dina S. , Asgari Nasrin , Webster Gill , Khorooshi Reza 
Published: September 2020

AbstractMyeloid cells represent the major cellular component of innate immune responses. Myeloid cells include monocytes and macrophages, granulocytes (neutrophils, basophils and eosinophils) and dendritic cells (DC). The role of myeloid cells has been broadly described both in physiological and in pathological conditions. All tissues or organs are equipped with resident myeloid cells, such as parenchymal microglia in the brain, which contribute to maintaining homeostasis. Moreover, in case of infection or tissue damage, other myeloid cells such as monocytes or granulocytes (especially neutrophils) can be recruited from the circulation, at first to promote inflammation and later to participate in repair and regeneration. This review aims to address the regulatory roles of myeloid cells in inflammatory diseases of the central nervous system (CNS), with a particular focus on recent work showing induction of suppressive function via stimulation of innate signalling in multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE).
Elite female athletes’ experiences and perceptions of the menstrual cycle on training and sport performance
Authors: Brown Natalie , Knight Camilla J. , Forrest (née Whyte) Laura J. 
Published: September 2020

The purpose of the current study was twofold (a) to examine elite female athletes’ experiences of their menstrual cycle, with a focus upon the impact on training and competition performance and (b) the openness of conversation pertaining to the menstrual cycle with coaching and support staff. Following receipt of institutional ethical approval, individual semi‐structured interviews were conducted with 17 elite female athletes (25.5 ± 4.7 years) from multiple sports. Results revealed athletes’ experiencing a natural menstrual cycle reported physical symptoms alongside mood disturbances and reduced motivation to train. The decision to actively control the menstrual cycle was often triggered by a desire to reduce the effect on competition, to lessen anxieties about making required weight or reduce distraction to manage during competition. Athletes indicated an openness to talk about the menstrual cycle to other females, however, there was variation in the comfort athletes experienced regarding talking to male coaches. Overall, the findings highlight the need to educate elite athletes and coaches on the menstrual cycle, considering it in the same light as other physiological functions in sport to improve health, well‐being, and performance. Furthermore, providing education on how to construct positive conversations, equipping individuals with the correct terminology, and confidence to talk about the menstrual cycle will reduce some reservations identified through improved knowledge and understanding.
The Effect of Heat Transfer on Turbine Performance
Authors: Jardine Lachlan J. , Miller Robert J. 
Published: September 2020

Abstract
For over 50 years, high-pressure gas turbine blades have been cooled using air bled from the compressor. This cooling results in very high rates of heat transfer, both within the fluid and within the blade, shown in figure 1. The heat transfer often occurs across large temperature differences and is thus highly irreversible. It is therefore surprising that little is understood about the effect of this heat transfer on turbine performance.
Effect of Binder Constituents and Solids Loading on the Rheological Behavior of Irregular Iron-Based Feedstocks
Authors: Tafti Atefeh A. , Demers Vincent , Vachon Guillem , Brailovski Vladimir 
Published: September 2020

Abstract
This work presents an experimental approach used to evaluate the influence of binder constituents and solids loading on the rheological behavior and molding properties of irregular shape iron-based feedstocks used in low-pressure powder injection molding (LPIM). Thirty-six (36) different feedstocks formulated from one new in-development iron-based powder and different wax-based binder systems (paraffin wax (PW) with surfactant and thickening agents) were obtained for solids loading varying from 50 to 68 vol%. The viscosity profiles were experimentally measured at different temperatures using a rotational rheometer in order to quantify the threshold proportions of each ingredient in the binder systems, identify the best feedstock candidates, and calculate their moldability indices, which were finally validated using real-scale injections. Results confirmed that the best feedstock formulation was the one containing paraffin wax with 1 vol% stearic acid (SA) used as a surfactant, 2 vol% ethylene-vinyl acetate (EVA) used as a thickening agent, and 2 vol% carnauba wax (CW) used as a shrinking agent. An irregular shape iron-based feedstock with maximum solids loading of 58 vol% was successfully injected.
Antiwear Properties of Commercial Grease as a Function of Particle Morphology and Uniformity of the As-Synthesized Calcium Carbonate Additive
Authors: Akhtar Khalida , Yousafzai Saniya 
Published: September 2020

AbstractCalcium carbonate powder comprising uniform nanoparticles of novel morphology was synthesized under extensively optimized trial parameters. The as-prepared ultrafine rod shape CaCO3 particles after characterizations were used as an antiwear/antifriction additive in commercial lithium grease (CLG) of different specifications. The effect of the added particles on the antifriction and antiwear properties of the blended commercial greases was explored by using a ball-on-disk tribometer. The observed data were compared with the additized grease having commercially available CaCO3 powder. Results exposed that uniformity in particle size and shape is a key factor for the improvement of tribological properties and reproducibility of the experimental results. Therefore, the as-prepared monodispersed rod shapes CaCO3 particles as additives considerably improved the tribological properties of the CLG as compared with the irregular particles of the commercial calcium carbonate. These blends showed the best results at the optimum amount of 3 wt% of the added CaCO3 particles. Among the three selected greases, the additized Momin grease exhibited best antiwear/antifriction performance as compared with the additized Awami and Sinopec greases.
Effect of Transfer Films on Friction of PTFE/PEEK Composite
Authors: Qu Shuren , Lo King Him , Wang Su Su 
Published: September 2020

Abstract
This paper investigates the effect of transfer films on friction coefficient of polytetrafluoroethylene (PTFE)/polyetheretherketone (PEEK) composite. Friction experiments were carried out first to investigate transfer-film development during sliding contact of PTFE/PEEK composite with different PTFE volume fractions on a steel counterface. Quantitative relationships between PTFE/PEEK composite friction coefficient and constituent material mechanical properties are then established to facilitate the subsequent investigation of friction mechanisms and influence of transfer films on the composite friction. A micromechanics-based friction theory is developed for predicting PTFE/PEEK composite friction coefficient. The effect of transfer films on composite friction is accounted for based on two distinctly different mechanisms—one with solid-state film lubrication and the other with PTFE as a solid-state lubricant on the top surface of transfer films. The friction theory is first validated through the excellent agreement obtained between the theoretical predictions and the in-house experimental results on PTFE/PEEK composite with up to 20% PTFE (by volume). The validity of the theory is further demonstrated by comparing the theoretical predictions with the test data reported by other researchers in the literature.
Investigation of Tangential Contact Damping of Rough Surfaces From the Perspective of Viscous Damping Mechanism
Authors: Pan Wujiu , Li Hongshuang , Qu Haoyong , Ling Liangyu , Wang Linlin 
Published: September 2020

AbstractThe contact damping between rough surfaces has an important influence on the wear, vibration, contact fatigue, and energy dissipation between interfaces. In this paper, based on contact theory, a tangential damping mathematical model of rough surfaces is established from the point of view of viscous contact damping energy dissipation mechanism of asperities and considering the fractal characteristics of three-dimensional topography of rough surfaces. Through the combination of micro-contact modeling and macro dynamic testing of composite beams, the analysis results show that there are important evolution rules between tangential damping and surface fractal parameters and material parameters. The nonlinear relations between them are as follows: tangential contact damping is positively correlated with normal load, load ratio, and maximum contact area of asperity, and negatively correlated with fractal roughness; tangential contact damping increases first and then decreases with the increase of three-dimensional fractal dimension. The results of computational and experimental modal analysis show that the established mathematical model is feasible for predicting tangential damping. The study of tangential contact damping between surfaces can lay a foundation for improving the performance of assembly interfaces.
Trajectory Tracking Control for Rotary Drilling Systems Via Integral Sliding Mode Control Approach
Authors: Weng Chien-Chih , Karkoub Mansour , Yu Wen-Shyong , Her Ming-Guo , Chen Hsuan-Yi 
Published: September 2020

Abstract
Active and passive control techniques have been devised over the years to mitigate the effect of vibrations on drill-string life with varying degrees of success. Here, it is proposed to design a robust trajectory tracking controller, which ultimately forces the rotary table and the drill-bit to move with the same speed (speed synchronization), hence reducing/eliminating torsional vibrations from the drill pipes. A model of the rotary drilling system, which includes torsional stick-slip, is first developed; then, an integral sliding mode control with time-varying exponent (ISMC-TVE) scheme is developed such that the bit motion tracks that of the rotary table to mitigate the effects of the induced vibrations. The ISMC-TVE is able to control the transient stage of the drill-string system’s response, maintain the system in the sliding state even under abrupt or existing external disturbances, and guarantee asymptotic stability of the rotary drilling system. The Lyapunov stability theorem is used here to analyze the performance of the closed-loop system, and the simulation results showed that the ISMC-TVE law is capable of accurately synchronizing the bit and rotary table speeds.
An Efficient Aeroelastic Eigenvalue Method for Analyzing Coupled-Mode Flutter in Turbomachinery
Authors: Huang Huang , Liu Wei , Petrie-Repar Paul , Wang Dingxi 
Published: September 2020

Abstract
In this paper, a method for analyzing flutter for a turbomachinery row with aerodynamically coupled structural modes is presented. The majority of observed turbomachinery flutter incidents involve only one structural mode family due to high mass ratio, high solidity and significant natural frequency separation for blades of traditional design. However, with the trend of higher aerodynamic loading, the wide usage of light weight composite materials and lower blade counts, the likelihood of coupled-mode flutter increases, particularly for turbofans or open rotors. Under such circumstances, the widely used energy method for flutter analysis is not valid. To model this situation, a novel aeroelastic eigenvalue method that is capable of modeling both single- and coupled-mode flutter is proposed. This method takes into account the aerodynamic coupling effects between different vibration modes through the influence coefficient cross sub-matrices, which can be efficiently computed by a harmonic balance solver. The new method is efficient as the required computational effort is only two times that of the traditional single mode analysis approach. The new method is demonstrated and validated by presenting results for Standard Configuration Eleven and NASA Rotor 67 flutter test cases in this paper.
Designing Representative Model Worlds to Study Socio-Technical Phenomena: A Case Study of Communication Patterns in Engineering Systems Design
Authors: Chaudhari Ashish M. , Gralla Erica L. , Szajnfarber Zoe , Grogan Paul T. , Panchal Jitesh H. 
Published: September 2020

Abstract
The engineering of complex systems, such as aircraft and spacecraft, involves large number of individuals within multiple organizations spanning multiple years. Since it is challenging to perform empirical studies directly on real organizations at scale, some researchers in systems engineering and design have begun relying on abstracted model worlds that aim to be representative of the reference socio-technical system, but only preserve some aspects of it. However, there is a lack of corresponding knowledge on how to design representative model worlds for socio-technical research. Our objective is to create such knowledge through a reflective case study of the development of a model world. This “inner” study examines how two factors influence interdisciplinary communication during a concurrent design process. The reference real world system is a mission design laboratory (MDL) at NASA, and the model world is a simplified engine design problem in an undergraduate classroom environment. Our analysis focuses on the thought process followed, the key model world design decisions made, and a critical assessment of the extent to which communication phenomena in the model world (engine experiment) are representative of the real world (NASA’s MDL). We find that the engine experiment preserves some but not all of the communication patterns of interest, and we present case-specific lessons learned for achieving and increasing representativeness in this type of study. More generally, we find that representativeness depends not on matching subjects, tasks, and context separately, but rather on the behavior that emerges from the interplay of these three dimensions.
On Design and Analysis of Electrostatic Arch Micro-Tweezers
Authors: Alneamy Ayman M. , Heppler Glenn R. , Abdel-Rahman Eihab M. , Khater Mahmoud E. 
Published: September 2020

Abstract
This article provides criteria for the design of electrostatic arch micro-tweezers. The tweezers can be operated in two modes: a traditional quasi-static mode where a direct current voltage commands the tweezers arms along a trajectory to manipulate objects and dynamic mode where a harmonic signal commands release or characterization of objects. While the arms are rigid and move in tandem in the static mode, this is not guaranteed in the dynamic mode. To satisfy this, we carried out modal analysis of the tweezers using a finite element model (FEM) and a reduced-order model (ROM). The results show that the arms kinetic and potential energies divide the beam span into a middle sub-span between the arms and two outer sub-spans and result in significant changes in the relative compliance of the sub-spans. The changes in the platform compliance place limitation on the tweezers dynamic operation, such that only the first symmetrical mode shape of the tweezers satisfies the design criteria. We also investigate the adequacy of an ROM using straight unbuckled beam mode shapes as basis functions to represent the tweezers response by comparing its results with those of FEM. A five-mode ROM is found adequate to represent small motions in the vicinity of the tweezers initial curvature. It is inadequate for larger motions involving snap-though motions between the initial and counter curvatures. To capture larger motions, ROM should be improved by incorporating higher order straight beam modes or using the actual tweezers modes.
Feasibility Study and Environmental Impact of Using a Photovoltaic System to Secure Relays of Mobile Communication Systems
Authors: Bentouba Saïd , Bourouis Mahmoud 
Published: September 2020

Abstract
Renewable energy sources are being considered an alternative for the provision of an uninterrupted supply of power to cover the extensive mobile services. The main purpose of this study is to determine a cost-effective way of achieving environmental sustainability of electricity supply in Global System for Mobile (GSM) communications mobile phone applications using photovoltaic systems. A specific installation of base transceiver stations and base station located in an arid and remote area was used as a case study. Using PV solar systems to secure a GSM relay in remote areas with hot climate is a very attractive alternative because of the solar irradiation accessible in the desert. The economic study carried out using the “Hybrid Optimization Model for Electric Renewable” simulation tool showed that the best configuration of the solar photovoltaic system for the case study in the present work consisted of 6 kW photovoltaic panels, 4 kW converter, and 24 storage batteries. The solar energy contribution in the electricity consumption was around 38%, and the other 62% was supplied by the power grid. The total net present cost (NPC) of the solar system was 43,946$. Regarding the environmental impact, all energy scenarios investigated showed a significant improvement in the environmental life cycle; especially the emissions of carbon dioxide were reduced by 65% by replacing the diesel generator backup system with the photovoltaic-assisted system.
Comparative Study of 16 Clear-Sky Radiative Transfer Models to Estimate Direct Normal Irradiance (DNI) in Botucatu, Brazil
Authors: Manoel dos Santos Cícero , Escobedo João Francisco , de Souza Amaury , Ihaddadene Razika , Gomes Eduardo Nardini , da Silva Maurício Bruno Prado 
Published: September 2020

AbstractThe interest of the direct normal irradiation (DNI) estimation is important in the evaluation of the solar potential and, consequently, for data correction and expansion of the historical series. In this study, a review of the performance of 16 models of radiative transfer was performed. These models are used to estimate DNI on a clear day in Botucatu/SP region located in Brazil. The revised models are categorized into two classes: simple models (11 models: ASH, MAJ, ALLEN, GH, P1, HLJ, FU, KU, H1, IP, and INC) and complex models (five models: BIRD, IQ, MRM5, P2, and YANG). The evaluation methodology used here is consistent with the literature. The input parameters were estimated and a statistical analysis using relative-mean-bias-error (rMBE), root-mean-square-error (rRMSE), and mean absolute percentage error (MAPE) indicators were performed to validate those models. The results indicate that the complex models (that require more atmospheric inputs) generally performed better than simpler models. Despite the consistent limitations in the use of estimated parameters, the performance of the models can be considered satisfactory. The best performances are highlighted for models MRM5 and YANG. Simple models ASH and IP performed similar to complex models. These results were confirmed using frequency distribution and the cumulative frequency analysis. These results are important for engineers of solar systems to use the best model and select the most suitable locations for installing a small or large solar plant.
Numerical Simulation of Direct Solar Vapor Generation of Acetone for an Organic Rankine Cycle Using an Evacuated Tube Collector
Authors: Dami Kajewole Emmanuel , Beltran-Chacon Ricardo , Islas Saul , Leal-Chavez Daniel 
Published: September 2020

Abstract
This paper analyzes the direct solar vapor generation of acetone by solar radiation falling on the heat pipes of an evacuated tube collector (ETC) that can activate a domestic scale organic Rankine cycle (ORC). The irradiance from the sun determines the mass flow of acetone along the horizontal manifold of the ETC to produce vapor at the collector outlet. A scilab code is developed to simulate the flow of acetone inside the manifold where subcooled acetone undergoes heating and evaporation process. Simulation is run from 60 °C to a saturation temperature of 120 °C at a pressure of 604 kPa, vapor qualities from 1% to 100%, and solar radiation from 300 to 1100 W/m2. The Kattan–Thome–Favrat flow boiling model is used to obtain the two-phase local heat transfer coefficients along the horizontal manifold, and it is validated with the numerical and experimental values of ammonia. The ORC system can generate 218 kWh/year of electrical energy, a thermal power capacity of 1616 kWh/year and achieve an ORC efficiency of 84.4%. The solar-ORC has a thermal efficiency of 3.25% and an exergy efficiency of 21.3% with a solar collector of 2.84 m2.
General ADRC Design for Systems With Periodic Disturbances of Unknown and Varying Frequencies
Authors: Madonski Rafal , Stankovic Momir , Ferdjali Abdellah , Shao Sally , Gao Zhiqiang 
Published: September 2020

Abstract
A new active disturbance rejection control-based (ADRC) scheme is proposed in this work to address the problem of tracking/rejecting periodic signals of unknown and varying frequencies. The frequencies are obtained online with a dedicated adaptive estimator and used in real-time as partial model information to an observer that reconstructs (among other things) the negative influence of periodic terms on the controlled output. A continuously updated two-tier control action is then applied to compensate the periodic interference and govern the resultant (simplified) plant dynamics. The proposed control topology is derived here in its general form and validated with an experimental case study.
Experimental Validation of an Intelligent Hybrid Plain Bearing Active Control
Authors: Eberhardt Clément , Kurth Robin , Kraft Christian , Schwarze Hubert , Päßler Thomas , Bergmann Markus , Putz Matthias 
Published: September 2020

Abstract
The replacement of damaged journal bearings in forming machines eventuates in very high personal and material costs as well as long-term downtime. Moreover, new discontinuous forming processes (e.g., press hardening and pendulum operations) have a negative effect on the hydrodynamic pressure built up in the bearing and can lead to failure. Therefore, users and manufacturers of forming presses are looking for ways to improve the safety of this key component. In this paper, the concept of an intelligent hybrid plain bearing (IHPB) that combines hydrodynamic and hydrostatic characteristics, presented by Kurth et al., (2019, “Forming 4.0: Smart Machine Components Applied as a Hybrid Plain Bearing and a Tool Clamping System,” Proc. Manuf., 27, pp. 65–71), is detailed and validated on a test rig. The clearance state of the journal bearing is monitored through eddy current sensors and a controlled hydrostatic support is activated, when this state is evaluated as critical. The results show a strong increase in the load capacity and in the minimal lubrication gap of the IHPB within three series of tested experiments: stationary, nonstationary, and press-typical load cases.