bluuebunny/crossref_metadata_2025 huggingface dataset:
Patient's experiences of endotracheal tubes and suction following cardiac surgery
Authors: Gilder Eileen , Jull Andrew , Slark Julia , Parke Rachael L.
Published: February 2021

Background

There is a growing body of evidence addressing the patient experience of intensive care, including patient reports that the presence of an endotracheal tube is bothersome and distressing, and that endotracheal suction is moderately to extremely painful. Yet there remains little information about the patient experience of the endotracheal tube and suction in those patients receiving planned short‐term mechanical ventilation.

Aims and objectives

This study aimed to describe the patient experience of the endotracheal tube and suction, following mechanical ventilation in post‐operative cardiac surgical patients.

Design

This qualitative study used inductive thematic analysis. Participants having planned cardiac surgery, anticipated to receive less than 12‐hours mechanical ventilation, were approached pre‐operatively and written consent provided.

Methods

Ten participants were recruited using purposive sampling. Semi‐structured interviews were conducted between days four and six post‐operatively. One researcher interviewed all participants; two researchers independently read, coded, and agreed themes.

Findings

None of the participants recalled endotracheal suction, while half had no recollection of the endotracheal tube. Three themes were identified; the experience of the endotracheal tube and extubation, the experience of emerging from sedation, and participants concerns about the future. The presence of the endotracheal tube was described as bothersome, whilst breathing through the tube and extubation were described as 'weird' and 'strange' but not painful.

Conclusions

Knowledge of the patient experience can help inform nursing practice by improving pre and post‐operative care planning.

Relevance to clinical practice

This study adds to the body of knowledge about the patient experience of the endotracheal tube and extubation.

Trial registration

Prospective registration with the Australian New Zealand Clinical Trials Registry. www.anzctr.org.au (ACTRN12616001515482).
Motor patterns in the proximal and distal mouse colon which underlie formation and propulsion of feces
Authors: Costa Marcello , Keightley Lauren J. , Hibberd Timothy J. , Wiklendt Lukasz , Dinning Phil G. , Brookes Simon J. , Spencer Nick J.
Published: February 2021

Background

In herbivores, the proximal and distal colonic regions feature distinct motor patterns underlying formation and propulsion of fecal pellets, respectively. Omnivores, such as mice and humans, lack a similar clear anatomical transition between colonic regions. We investigated whether distinct processes form and propel content along the large intestine of a mouse (an omnivore).

Methods

We recorded propulsive and non‐propulsive neurogenic motor activity in mouse large intestine under six different stimulus conditions of varying viscosities. Gut wall movements were recorded by video and smooth muscle electrical behavior recorded with extracellular suction electrodes.

Key Results

Three major neurally mediated motor patterns contributed to pellet formation and propulsion. (1) Pellet‐shaped boluses are pinched off near the ceco‐colonic junction and slowly propelled distally to a transition located at 40% length along the colon. (2) At this functional colonic flexure, propulsion speed is significantly increased by self‐sustaining neural peristalsis. Speed transition at this location also occurs with artificial pellets and with spontaneously formed boluses in the empty colon. (3) Periodic colonic motor complexes (CMCs) were present in all conditions reaching a maximal frequency of about 0.4 cpm and extending across the proximal and distal colon with faster speed of propagation.

Conclusions and Inferences

The three motor patterns share a unique underlying fundamental property of the enteric circuits, which involve extended ensembles of enteric neurons firing at close to 2 Hz. The demonstration of distinct functional differences between proximal and distal colon in rabbit, guinea pig, and now mouse raises the possibility that this may be an organizational principle in other mammalian species, including humans.
Elektra from the lower depths?
Authors: Jakubova Natalija
Published: February 2021

The role of women artists in the theatre reform of the early twentieth century is usually underestimated. This paper strives to reassess the agency of a female performer (Gertrud Eysoldt) in this process, concentrating on the premiere production ofElektraby Hugo von Hofmannsthal (1903, Kleines Theater, Berlin). Hofmannsthal wrote his version ofElektranot only for Max Reinhardt’s company (which he considered to be a new kind of theatre) but also specifically for Eysoldt, and this article focuses on the communication between them. The main sources for this research are texts written by the actress: her article for a newspaper and her letters to Hofmannsthal (published in 1996) and Hermann Bahr (unpublished, Austrian Theatre Museum, Vienna). These texts are analysed more from the perspective of their poetics than from the perspective of the facts they convey. Eysoldt’s autobiographical writings reveal an unexpected facet of the 'Dionysism' that may have attracted Hofmannsthal. Finally, a question is raised about the meaning of the shift that Hofmannsthal made by offering the performer a rewriting of a foundational myth of patriarchal culture.
Proposed Pipelines and Environmental Justice: Exploring the Association between Race, Socioeconomic Status, and Pipeline Proposals in the United States*
Authors: Strube Johann , Thiede Brian C. , Auch Walter E. “Ted”
Published: February 2021

The current natural gas and oil boom in North America requires new pipelines, which pose environmental risks from wellheads to their destinations. The environmental justice literature suggests that ethno‐racial minorities, populations with low socioeconomic status, and rural communities are disproportionally exposed to risks associated with potentially harmful land uses. Using data from the American Community Survey's 2015 five‐year estimates and data on the route of proposed pipelines compiled by The FracTracker Alliance, this study tests whether the above assumptions are true for proposed FERC‐permitted natural gas transmission pipelines in the United States for which planned routes have been made available. The results of logistic regression models provide only limited, and in some cases contradictory, support for these hypotheses. Although an increased share of highly educated residents significantly decreases the likelihood of a pipeline proposal in a census tract, a higher poverty rate also significantly lowers this probability. Likewise, the share of Black and Hispanic residents is significantly and negatively associated with pipeline proposals. However, reliable routing data are needed to test whether this holds true for built pipelines, but these data are considered confidential and thus inaccessible in the United States.
A novel pre‐emergence herbicide (Diclosulam) as an environmentally friendly weed management option in peanut and its phytotoxicity evaluation
Authors: Meena Har N. , Yadav Ranjeet S. , Jain Navin K. , Yadav Mayank
Published: February 2021

A two‐season field experiment was conducted to evaluate the efficacy of diclosulam compared with recommended doses of pendimethalin and oxyfluorfen for weed management in peanut. Persistence of diclosulam in oil, de‐oiled cake, haulm of peanut, and soil was also studied. Diclosulam 22 and 26 g a.i. ha−1, and a weed‐free check had a high pod yield due to more mature pods and their mass. Pre‐emergence application of diclosulam 26 g a.i. ha−1provided better weed management and enhanced peanut growth and yield with high net returns. Phytotoxicity studies indicated that the diclosulam application did not cause any phytotoxic symptoms (vein clearing, epinasty, hyponasty, wilting, and injury) on leaf tips and leaf surface of peanut. Diclosulam residues in peanut viz. oil, de‐oiled cake, haulm, and soil were below the detection level after harvesting of peanut from the experimental field. Further, germination percentage and seed cotton yield of cotton crop cultivated after peanut were also not affected significantly.
Heterogeneidad de la estructura ocupacional, desigualdad distributiva y obstáculos a la equidad en la Argentina (1974-2014)
Authors: Salvia Agustín , Poy Santiago , Vera Julieta
Published: February 2021

El artículo examina el comportamiento de la desigualdad de la distribución del ingreso familiar bajo los distintos regímenes macroeconómicos vigentes en las últimas cuatro décadas en la Argentina y evalúa los factores que explican sus cambios. Se examina la hipótesis de que, tras la desarticulación del modelo de industrialización por sustitución de importaciones, se habría profundizado la heterogeneidad estructural del sistema ocupacional argentino, lo que tendría consecuencias sobre el patrón de desigualdad socioeconómica. Para abordar esta hipótesis, se lleva adelante un modelo de descomposición del coeficiente de Gini distinguiendo el aporte de los ingresos de distintos sectores económicos en la desigualdad de ingresos familiares. La información se construyó a partir de la Encuesta Permanente de Hogares del Instituto Nacional de Estadística y Censos de Argentina, correspondientes al Área Gran Buenos Aires, por ser la única para la que existe información durante el conjunto del período. Los hallazgos revelan que la mayor desigualdad distributiva se explica por la mayor inequidad de los ingresos laborales, la mayor concentración de ingresos por parte de los sectores económicos más modernos y por un empobrecimiento del sector de baja productividad.
Mayo del 68 y sus interpretaciones
Authors: Gómez Albarello Juan Gabriel
Published: February 2021

Mayo del 68 ha sido caracterizado e interpretado de muchas maneras. En este artículo doy cuenta de tres de las caracterizaciones más importantes: una crisis política, un psicodrama y un carnaval, así como una crisis de la civilización. También señalo las razones por las cuales creo que Raymond Aron tiene razón en la mayoría de sus planteamientos acerca de lo ocurrido hace 50 años y hago referencia a las razones por las cuales el legado de Mayo del 68 sería imposible de reclamar. Sin embargo, sostengo que la crítica antijerárquica de los estudiantes parisinos requiere ser tomada mucho más seriemente. Para ello, reflexiono sobre los planteamientos del neurocientífico Henri Laborit.
Movimientos feministas transnacionales en América Latina y el Caribe. Contribuciones para el estudio del activismo europeo
Authors: Perea Ozerin Iratxe
Published: February 2021

El artículo aborda la construcción de Movimientos Sociales Transnacionales (MST) en escenarios regionales, enfocado en el activismo feminista latinoamericano y del caribe en el contexto de la lucha contra la globalización neoliberal desde los años ochenta. El enfoque regional sobre los MST es relevante porque, aunque estos actores están moldeados por identidades y repertorios colectivos globales, también están arraigados en condiciones locales, nacionales y regionales específicas. Las condiciones sociohistóricas en una región llevan a las identidades colectivas que dan forma a los MST regionales que, a su vez, tienen un impacto sobre la articulación de los MST globales y sobre la dinámica de la contestación global. De hecho, estas identidades y repertorios transnacionales articulados regionalmente se transmiten luego a los MST globales. El artículo analiza el Movimiento Feminista Transnacional Latinoamericano (MFT) y, teniendo en cuenta el presente estudio de caso, discute el proceso de construcción del movimiento en la lucha feminista contra la austeridad en Europa después de la crisis de 2008. Se analiza la formación de identidades

colectivas feministas y la organización de espacios transnacionales que puedan conducir al surgimiento de un MFT europeo con capacidad para actuar en el ámbito internacional como actor unitario
Fatigue of Shafts at Fitted Members, With a Related Photoelastic Analysis
Authors: Peterson R. E. , Wahl A. M.
Published: February 2021

This paper deals primarily with the fatigue of shafts with press-fitted members, a problem frequently arising in connection with rotating machinery involving gears, wheels, couplings, rotors, etc. Failures at the edge of fitted members are not uncommon in practice. A survey is made of existing data, after which a report of fatigue tests on the press-fit problem carried out at the Westinghouse Research Laboratories is given. A related photo-elastic investigation and stress analysis is also reported. Practical expedients for increasing the strength of shafts with fitted members are given. Suggestions for future research along the foregoing lines are made throughout the paper.
Pitting Due to Rolling Contact
Authors: Way Stewart
Published: February 2021

Pitting, as the term is used in this paper, means a form of failure which occurs on gear teeth near the pitch circle, on rollers, in anti-friction bearings, and on other machine parts where cylindrical surfaces come in rolling contact under heavy loads. The purpose of the investigation described in this paper is to study the manner in which pits develop, to discover the reason for their development, and to find what conditions must be fulfilled to prevent their occurrence.

A testing machine was used in which steel rollers approximately 1.5 in. in diameter, rolling together and loaded as shown in Fig. 2, could be tested. More than eighty tests have been made with rollers of different materials, with different lubricants, and with various loads.

Pits are found to have a definitely characteristic shape and orientation with respect to the direction of rolling. They were observed to develop from minute cracks in the roller surfaces which appear after about 500,000 revolutions. Photographs were taken tracing the growth of these pitting cracks from their earliest observed stage. The cracks from the very beginning have a characteristic shape and orientation.

The principal findings in the tests on the steel rollers were: (1) That a lubricant must be present if pitting is to take place; (2) that if the lubricant is of a viscosity above a certain critical value which depends on the load, pitting can be prevented; (3) that the nature of the surface finish on the rollers greatly influences the tendency to pit, pitting being prevented on a highly polished surface and accelerated on a rough-machined surface; (4) that nitrided rollers will not pit under conditions that would result in severe pitting of quenched and tempered mild carbon-steel rollers, also that pits are smaller on harder surfaces, in general.

In the theoretical section of the paper, the load-carrying capacity for the oil film between two rollers having a common peripheral velocity is calculated, and it is shown that the critical viscosity necessary to prevent pitting is far below that necessary to prevent metal-to-metal contact, a fact also checked experimentally. The normal and tangential oil forces on the rollers after metal-to-metal contact are also calculated, and the tangential component is found to be small compared with the normal component. Calculation showed that no tensile stress would exist at the surface, where pitting cracks appear to start, due to contact pressure or oil forces. However, it is found by analysis that a small crack in the surface, if filled with oil, will tend to grow, provided it has a certain initial direction. This direction is the same as that of the cracks which precede pitting. This strongly suggests that oil penetration of very small surface cracks with a certain initial direction is the reason for the growth of these cracks until a particle is separated from the main body of material, leaving a pit. The experimental results harmonize, also, with this theory.
Thermal Stresses in Plates
Authors: Maulbetsch John L.
Published: February 2021

The author presents solutions of the problem of thermal stresses in thin plates of uniform thickness with simply supported edges when the temperature varies only along the thickness of the plate. For the case of polygonal-shaped plates it is shown that the solution can be deduced from the problem of the torsion of prismatical bars, the cross section of which has the same shape as the plate. The exact solutions for cases of equilateral triangular and square plates are given. Although only the case of small deflections is considered, its limitations are treated in detail.
Study for Control of Dimensional Distortion in Tempered Industrial Parts
Authors: Scheidemantel João Alfredo , Doré Christian , Peruzzo Lucile Cecília
Published: February 2021

The presence of residual stress generated in the manufacturing process defines one of the biggest problems found in the mechanical metal industry. In the search of mechanical properties to a specific application, it is mandatory to impose the parts at very critical mechanical, chemical or thermal requests. The study analyzes all the steps that apply considerable stresses to the component during the manufacturing process and, therefore, discover which ones add more stresses to the yield limit of the material. It was also intended to contribute with relevant information regarding the surface integrity of the material, with bigger coverage in the residual stresses generated where, due to their nature and expressiveness, they can be beneficial or harmful to the component’s useful life. Accordingly, the objective was to analyze the raw material of SAE 4140 steel through its microstructure and verification of its chemical and mechanical characterization. In order to reduce the occurrence of dimensional distortions in excess of tolerance, we sought to identify the most critical step and, therefore, act with viable possibilities and without relevant costs for the prevention of the problem encountered. In order to measure its stress and define the process in which the highest inclusion of residual tractive stresses is characterized, these being the deleterious ones for the process and for the product, we used the method of measuring residual stresses by ray diffraction in X. In your measurement, the stresses included on the surface of the specimens were measured at specific stages of the process. X-ray diffraction analysis analyzes the diffraction planes and their respective interplanar distances from a specific material, as well as the densities of atoms along the crystalline planes. Using mathematical models, it is possible to measure the residual stress existing in the investigated parts. In view of the analysis by X-ray diffraction, it was verified the existence of disordered variations and modifications of the crystalline phases on the material surface, at the end of the finish machining process. These crystalline phases which, together with a less aggressive fabrication, favor plastic deformation due to the presence of residual stresses which surpass those of the yield limit of the analyzed material. In this sense, it was possible to determine which the most critical operation related to the component request is the machining in which it is applied. Since the subsequent processes only aggravates this condition, resulting in an unusable component for the proposed application without adding a higher cost to the product, either through the use of some rework or scrap procedure.
Fatigue Properties of 3D Welded Thin Structures
Authors: Allameh Seyed M. , Lenihan Avery , Miller Roger , Allameh Hadi
Published: February 2021

Additive manufacturing technology has matured enough to produce real industrial components. A newer method of 3D printing is the deposition of molten metal beads using a MIG weld torch. This involves a 3D printer equipped with a MIG torch layering the metals in desired shapes. It allows the fabrication of components made of MIG weld wires, currently available from various elements including Cu, Al, steel and alloys. Some of these structures made by 3D welding will have applications in critical load bearing conditions. The reliability of such components will be vital in applications where human lives are at stake. Tensile tests are conducted to verify the required strength of the fabricated parts which will undergo monotonic loading; however, fatigue tests are required for cases where cyclic loading will take place. Conventional tensile and fatigue testing requires macro-scale samples. With MIG welding, it is possible to make thin-walled structures. Fatigue testing on samples extracted from thin walls is made possible by microtesting. This study is focused on the mechanical properties of 3D welded structures made from MIG welding wires. Our earlier results showed orientation dependence of mechanical properties in 3D welded structures. They also showed the effect of substrates in expression of the orientation dependence. Welding on metal substrate produces weld beads that are harder at the substrate interfacial area. However, for structures welded on ceramics, the opposite is true. They exhibit a softer substrate interfacial area and a relatively harder top. Our newer results show fatigue properties of structures made by 3D welding. Microsamples measuring 0.2 mm × 0.2 mm × 1.0 mm were extracted from metal beads using a CNC mill along with an EDM. The contours of the samples were machined by milling and the back side was cut by electro discharge machining. Specimens were then polished to the desired size and mounted in the grippers of an E1000 Instron load frame. WaveMatrix® application software from Instron was used to control the machine and to obtain testing data. Fatigue tests were performed, and life cycles were determined for various stress levels up to over 5 million cycles. The preliminary results of tensile tests of these samples show strength levels that are comparable to those of parent metal, in the range of 600–950MPa. Results of fatigue tests show high fatigue lives associated with relatively high stresses. The preliminary results will be presented and the implications of the use of 3D welded rebar in 3D printing of reinforced concrete structures will be discussed.
Characterizing Additively Manufactured Metals From a Novel Laser Wire Metal Deposition Process
Authors: Kumpaty Subha , Balu Renius Curtis , Pinnamaraju Abhiram , Schaefer Matthew , Gray Andrew , Woida Scott
Published: February 2021

Several tests were conducted on 316 stainless steel, and 17-4 PH stainless steel to understand the effect of additive manufacturing on their mechanical properties in general. The samples were produced via a custom-built laser wire metal deposition, with variable laser power of 3600W for 316 stainless, and 4000W for 17-4 PH, but all other printing parameters were kept same. Four different tests, Tensile, Rockwell hardness, Charpy impact, and optical microscopy were carried out to establish the material properties and surface characterization. Through our assessment, it was found that the properties of the laser-printed samples can be greatly varied by printing in an inert atmosphere, while the printing orientation and post-print heat treatment process also play a dominant role in determining the properties. This research showed that the properties of additively manufactured 316 stainless, and 17-4 PH have fared well when compared to ASTM standard values for annealed metals. Details of the results are presented.

Inspecting the 316 stainless, the metal strength and hardness were high while being printed in x orientation, while the metal was much more ductile when printed in y orientation. The 316 stainless micro-structure contained no porosity or no anomalies from the samples tested. The results of 17-4 stainless samples matched the ASTM standard values for strength and hardness. But with Charpy impact tests, the results seemed slightly ductile as the values were slightly lower than the threshold. That brittle nature could have been a result of porosity that was visible under microscope. But the porosity levels decreased tremendously when the sample was once again printed in an inert environment. The results of this research have helped us understand the intricate nature of 316 and 17-4 PH stainless steels while being additively printed. The beneficial research experience of participating undergraduate students in collaboration with industry is a special feature of this project.
Life Cycle Assessment of a Household in Ecuador
Authors: Ramirez Angel D. , Crespo Karla , Salas Daniel A. , Boero Andrea J.
Published: February 2021

The life cycle assessment (LCA) of a middle-class household of 5 members in Guayaquil, Ecuador was performed in order to identify the life cycle stages and activities with higher environmental burdens. LCA is a quantitative tool for assessing the environmental performance of products or systems during its life span, through the compilation and further evaluation of the inputs, outputs, and potential environmental impacts.

The life cycle of the house included a 50-year lifespan house divided into three stages: pre-occupation, occupation, and post-occupation stage. The type of house chosen for the analysis represents the current trend of urban growth and planning of the city, which is pointing towards residential zones and housing plans far away from central areas.

The notion of household metabolism is associated with the occupation stage. Household metabolism refers to all flows of matter and energy related to anthropogenic activities conducted on a household, which is a socio-economic entity that consists of people living together occupying a dwelling or part of it. Households are key entities of the anthroposphere because the sum of all private households is the process on which all other processes depend on and serve directly or indirectly. The total energy use and emissions for which the sum of households is responsible reflects the importance of considering its influence when assessing the environmental impact of dwellings.

Five energy case scenarios were analyzed. These included different energy mixes and the use of inductive cookers as an alternative to those that use liquefied petroleum gas (LPG), which are the most used in Ecuador. The influence of the energy production structure of the country on the environmental impact of the household is supported by the results. A higher share of hydroelectricity in the energy mix, compared with the share of thermal electricity, presented lower environmental impacts in most categories. Public policies that encourage a shift towards a cleaner electricity production technology may decrease the overall environmental impact of households and buildings.

The occupation stage entails the highest contribution to all impact categories, e.g. 88% of global warming potential (GWP), followed by the pre-occupation stage, contributing 10% of GWP. Food consumption has not been considered in reviewed studies, although it represents the highest environmental burden within the occupation stage of the house, followed by electricity, and gas use: 43, 27, and 20% of GWP respectively.

The results support the importance of including household metabolism in LCA studies due to the high environmental burden associated with it, and the influence of the electricity production structure of the country on the life cycle impact of households.
Investigating the Precipitation Kinetics and Hardening Effects of γ” in Inconel 625 Using a Combination of Meso-Scale Phase-Field Simulations and Macro-Scale Precipitate Strengthening Calculations
Authors: Yenusah Caleb O. , Ji Yanzhou , Liu Yucheng , Stone Tonya W. , Horstemeyer Mark F. , Chen Lei
Published: February 2021

Precipitation strengthening of alloys by the formation of secondary particles (precipitates) in the matrix is one of the techniques used for increasing the mechanical strength of metals. Understanding the precipitation kinetics such as nucleation, growth, and coarsening of these precipitates is critical for evaluating their hardening effects and improving the yield strength of the alloy during heat treatment. To optimize the heat treatment strategy and accelerate alloy design, predicting precipitate hardening effects via numerical methods is a promising complement to trial-and-error-based experiments and the physics-based phase-field method stands out with the significant potential to accurately predict the precipitate morphology and kinetics. In this study, we present a phase-field model that captures the nucleation, growth, and coarsening kinetics of precipitates during isothermal heat treatment conditions. Thermodynamic data, diffusion coefficients, and misfit strain data from experimental or lower length-scale calculations are used as input parameters for the phase-field model. Classical nucleation theory is implemented to capture the nucleation kinetics. As a case study, we apply the model to investigate γ″ precipitation kinetics in Inconel 625. The simulated mean particle length, aspect ratio, and volume fraction evolution are in agreement with experimental data for simulations at 600 °C and 650 °C during isothermal heat treatment. Utilizing the meso-scale results from the phase-field simulations as input parameters to a macro-scale coherency strengthening model, the evolution of the yield strength during heat treatment was predicted. In a broader context, we believe the current study can provide practical guidance for applying the phase-field approach as a link in the multiscale modeling of material properties.
Digital Twin: Collaborative Virtual Reality Environment for Multi-Purpose Industrial Applications
Authors: Kuts Vladimir , Otto Tauno , Bondarenko Yevhen , Yu Fei
Published: February 2021

Industrial Digital Twins (DT) is the precise virtual representation of the manufacturing environment and mainly consists of the system-level simulation, which combines both manufacturing processes and parametric models of the product. As being one of the pillars of the Industry 4.0 paradigm, DT-s are widely integrated into the existing factories, enhancing the concept of the virtual factories. View from the research perspective is that experiments on the Internet of Things, data acquisition, cybersecurity, telemetry synchronization with physical factories, etc. are being executed in those virtual simulations. Moreover, new ways of interactions and interface to oversee, interact and learn are being developed via the assistance of Virtual Reality (VR) and Augmented Reality (AR) technologies, which are already widely spread on the consumer market. However, already, VR is being used widely in existing commercial software packages and toolboxes to provide students, teachers, operators, engineers, production managers, and researchers with an immersive way of interacting with the factory while the manufacturing simulation is running. This gives a better understanding and more in-depth knowledge of the actual manufacturing processes, not being directly accessing those. However, the virtual presence mentioned above experience is limited to a single person. It does not enable additional functionalities for the simulations, which can be re-planning or even re-programming of the physical factory in an online connection by using VR or AR interfaces. The main aim of the related research paper is to enhance already existing fully synchronized with physical world DT-s with multi-user experience, enabling factory operators to work with and re-program the real machinery from remote locations in a more intuitive way instead thinking about final aim than about the process itself. Moreover, being developed using real-time platform Unity3D, this multiplayer solution gives opportunities for training and educational purposes and is connecting people from remote locations of the world. Use-cases exploits industrial robots placed in the Industrial Virtual and Augmented Reality Laboratory environment of Tallinn University of Technology and a mobile robot solution developed based on a collaboration between the University of Southern Denmark and a Danish company. Experiments are being performed on the connection between Estonia and Denmark while performing reprogramming tasks of the physical heavy industrial robots. Furthermore, the mobile robot solution is demonstrated in a virtual warehouse environment. Developed methods and environments together with the collected data will enable us to widen the use-cases with non-manufacturing scenarios, i.e., smart city and smart healthcare domains, for the creation of a set of new interfaces and multiplayer experiences.
Follower Behavior in Engineering Design Teams: Theoretical Constructs and Protocol Analyses
Authors: Plaunt Jessica A. , Ortiz Joshua B. , Agyemang Malena , Summers Joshua D.
Published: February 2021

The purpose of this research is to develop an understanding of followership behaviors in engineering design team situations by studying leadership behaviors. While leadership in engineering design teams has been studied from role, function or behavior, and individual characteristic perspectives, no studies are found that examined follower (helping) behavior in the context of an engineering design team. Understanding this behavior can lead to intervention strategies that might be employed to improve team dynamics and performance. To this end, a theoretical framework of follower behavior is defined based on a review of “helping behavior” from the literature. Characteristics of follower helping behavior include exhibiting citizenship, voluntary, extra-role, and not upsetting the status-quo. Specifically, a follower-leader is one who exhibits voluntary, “extra-role” (beyond expectation) behaviors in a professional setting done without upsetting the status-quo in a formal leadership setting. A model is developed that links leadership style, follower mindset, leader-follower relationship, influence tactics, follower behavior, and follower performance. The key behavior studied is helping behavior. This literature-based framework is exclusively based on survey study data. No research is found that focuses on studying the behaviors of followers from observational studies. Therefore, data presented from a previous protocol study is further reviewed in search of patterns of conversions of followers to leaders through behavior modeling. In the previous study, eight teams of four graduate engineering students were tasked with generating a function model for a design prompt. These teams were video recorded, and their behaviors coded for seven leadership actions. Of the eight design teams previously studied, there were 325 total leadership behaviors coded. A follower-to-leader behavior pattern was defined where a follower in one behavior immediately exhibited leadership behavior in the next coded activity. Of the activities coded, 131 (40.3%) possible follower helping actions have been identified. These are examined further to determine whether there is a correlation between the initial leadership behavior type and the following leadership behavior type. Patterns are also sought to determine how often the initial leader also changes to a follower in the subsequent activity. This study shows that there are follower patterns that are found in design activities. Further, these patterns are related back to the follower (helping) behavior model that is derived from the literature, specifically the influence tactics that include: inspirational appeals, consultation, supplication, and exemplification as well as the social exchange relationships of leader-member exchange (LMX), team-member exchange (TMX). Finally, this study provides suggestive evidence of patterns to motivate future systematic study of followership in engineering design.
Analytical Response of a Mass-Spring Oscillator With Time-Varying Inertia
Authors: Hassanpour Pezhmn
Published: February 2021

In this paper, the analytical response of a single-degree-of-freedom system with time-varying inertia is investigated. The system model represents several engineering systems, including resonant biosensors and load-carrying conveyor belts. The resonant biosensing applications, the mass of the resonator changes exponentially with time, while the mass of a load-carrying conveyor belt changes linearly. In general, the system’s inertial can increase or decrease. Considering that the first-order approximation of an exponential function yields a linear function, the latter function was used to model the variations of the mass with time with the assumption that the rate of change can be either positive or negative. The equation of motion is derived using newton’s second law of motion. Although the resultant ordinary differential equation has a similar form for both cases of increasing and decreasing mass, it is demonstrated that solving each case requires a different transformation, and the subsequent differential equations have different forms of analytical solutions. Each analytical solution is derived and compared with two corresponding cases: 1) the numerical solution of the differential equation with linearly-varying inertia, and 2) the numerical solution of the differential equation with exponentially-varying mass. Excellent agreement between the analytical solution and numerical solution of the system with linearly-varying inertia is demonstrated. This agreement confirms the validity of the analytical solution. On the other hand, the analytical solution agreed with the numerical solution of the system with exponentially-varying mass only for the initial moment of the integrations. This disagreement suggests that a linear approximation is not an accurate model for resonant biosensing applications where the mass variation is exponential by nature. Nevertheless, the linearly-varying mass model provides insights about how these systems behave differently from those with a constant mass. In particular, in this paper, it is demonstrated that an increasing mass system shows added damping effect. In contrast, a decreasing mass system behaves as if it has a “negative” damping coefficient. This finding is particularly significant because, along with other linear or nonlinear effects in the system that are not necessarily considered, it can produce catastrophically unwanted behaviors. Another impressive effect that is observed is the change of free vibration response of the system with time. For the case of increasing mass system, the frequency of oscillation of both linearly-varying and exponentially-varying systems decreases with time. In contrast, the frequency increases for the systems with decreasing mass. This phenomenon is expected because the frequency of free vibration is inversely proportional to the mass of the system.
Numerical Study of the Flow Inside a Modular Bag Filter From a Biomass Power Plant
Authors: Vinha Maria Inês , Silva João , Teixeira Senhorinha , Gomes Ana , Teixeira José Carlos
Published: February 2021

Nowadays, one of the most important issues in modern industrial power plants is air pollution. Solid particles are harmful to human health and are one of the main pollutants released through the combustion of biomass.

The main goal of this paper was to study the flow in a modular bag filter of a dedusting system implemented in a Biomass Power Plant, in order to improve the filtration of the solid particles coming from the biomass combustion. For this purpose, a numerical model using the ANSYS Fluent software was developed.

Initially, it was necessary to model the dedusting system in the software SolidWorks. Once this system had 10 modules and to facilitate the simulation in Fluent, only one module was modeled with proper simplifications. Once the geometry was modeled, it was exported to Fluent where the mesh was made, with special care in the inlet of the module, as it is the most critical zone for the simulation. It was simulated 4 cases, where the action of each individual filter was considered. The first case study considered the nominal operating conditions of a biomass power plant. Thereafter, two cases with different mass flow rates were simulated to assess if there were any differences in the flow inside the bag filter. Lastly, it was studied the influence of the vertical baffle size that is in the inlet of the module.

Comparing the four simulations, it was concluded that in the first three cases, the flow is very similar, with only a slight increase in the velocity in the study with higher flow, as expected. Furthermore, it was concluded that using a smaller vertical baffle, the flow would be improved, once the filters close to the inlet would be more used.
Evaluation of Control Algorithms on Mobile Robots for Collision Avoidance
Authors: Sungra Anshul , Fabien Brian
Published: February 2021

This paper describes the implementation of various algorithms to control the distance between a lead vehicle and a following (ego) vehicle. The ego robot equipped with a monocular camera and a rotating laser sensor (LDS). The monocular camera used for object detection using the Aggregate Channel Features (ACF) detection algorithm. The width of the bounding box generated by the detection algorithm had used to determine the distance between the lead and the following vehicles. Since this research focused on longitudinal autonomy, the data from the rotating laser sensor downsampled from 360 points to 30 points. These sampled points covered the front view of the vehicle. All data points transformed into a planar world coordinate (two-dimensional plane). The outputs of the camera and laser sensor (LDS) were fused to obtain accurate distance measurements for the lead vehicle. Sensor calibration had achieved by comparing sensor data with the ground truth values. Kalman Filter was used to implementing sensor fusion by combining perception data from the monocular camera and LDS for accurate position and velocity estimation. This calibration provided information about the sensor noise and deviation of sensor data from its ground truth values. These values helped to determine the error covariance matrixes of the Kalman filter. For implementation, the Robot Operating System (ROS)-MATLAB platform used to communicate between robot and host Personal Computer (PC). The experiments evaluated the performance of Proportional Control (P), Proportional-Integral Control (PI), and Model Predictive Control (MPC) in maintaining a minimum distance between the vehicles. For the MPC implementation in MATLAB, Model Predictive Control Quadratic Programming (MPCQP) solver was used to get the optimal solution for control output. The results show that the MPC yields faster response times when compared to P control and PI control. These algorithms evaluated during constant velocity and constant acceleration of the lead vehicle. The steady-state errors of P and PI controllers were around 0.1 meters (m) in both scenarios and 0 to 0.2m for constant velocity and 0 to 0.15m for ramp velocity, respectively. And for MPC, steady-state error varied from −0.05m to 0.05m in both the scenarios. This range in steady-state error was due to varying speed of the ego vehicle with time to maintain the minimum relative distance between the robots, and there was a communication delay in the system that also affected the behavior of the controllers. The MPC was more sensitive to communication delays. However, the effect of this communication delay was negligible to P and PI controllers. This sensitivity resulted in different velocity profiles for the ego vehicle in MPC and P or PI controllers.
Bridging Precipitate Microstructure and Mechanical Hardness of Nickel-Based Superalloy Through Artificial Neural Network Model
Authors: Li Yangping , Liu Yangyi , Luo Sihua , Wang Zi , Wang Ke , Huang Zaiwang , Zhao Haifeng , Jiang Liang
Published: February 2021

The attractive mechanical properties of nickel-based superalloys primarily arise from an assembly of γ′ precipitates with desirable size, volume fraction, morphology and spatial distribution. In addition, the solutioning cooling rate after super solvus heat treatment is critical for controlling the features of γ′ precipitates. However, the correlation between these multidimensional parameters and mechanical hardness has not been well established to date. Scanning electron microscope (SEM) images with different γ′ precipitates were investigated in this study, and artificial neural network (ANN) method was used to build a microstructure-mechanical property model. The critical step in this work is to extract different microstructural features from hundreds of SEM images. In order to improve the accuracy of prediction, the cooling rate was also considered as the input. In this work, the methodology was proved to be capable of bridging microstructural features and mechanical properties under the inspiration of material genome spirit.
Investigation of Grinding Force and Surface Integrity of IC10 in Creep Feed Grinding
Authors: Li Jun-chen , Wang Wen-hu , Jiang Rui-song , Liu Xiao-fen , Bo Huang , Jin Cheng-cheng
Published: February 2021

The IC10 superalloy material is one of the most important materials for aero-engine turbine blade due to its excellent performances. However, it is difficult to be machined because of its special properties such as terrible tool wear and low machined efficiency. The creep feed grinding is widely used in machining IC10 superalloy due to the advance in reducing tool wear, improving material removal rate and surface quality. The creep feed grinding is a promising machining process with the advantages of high material removal rate due to large cutting depth, long cutting arc and very slow workpiece, and its predominant features might have significant influence on the grinding force and surface quality for the workpiece. Hence, it is of great importance to study the grinding force and surface integrity in creep feed grinding IC10 superalloy.

In this paper, a series of orthogonal experiments have been carried out and the effects of grinding parameters on the grinding force and the surface roughness are analyzed. The topographies and defects of the machined surface were observed and analyzed using SEM. The results of the experiments show that the tangential force is decreased with the workpiece speed increasing. However, there is no significant change in tangential force with the increasing of grinding depth and wheel speed. The normal force is decreased with the workpiece speed increasing when the workpiece speed is less than 150 mm/min, but when the workpiece speed is more than 150 mm/min the normal force is increased tardily. Moreover, the normal force is increased sharply with the increase of grinding depth and is increased slowly with the increase of wheel speed. In general, the surface roughness is increased with workpiece speed and grinding depth increasing, while the trend of increase corresponding that of workpiece speed is more evident. The value of the surface roughness is decreased with wheel speed increasing. And it is found out that the main defect is burning of the IC10 superalloy material in creep feed grinding by energy spectrum analysis of some typical topography in this study.