bluuebunny/crossref_metadata_2025 huggingface dataset:
Rethinking ‘kampung’ or ‘village’ in the (re)making of Singapore and Singaporeans
Authors: Nallari Anupama , Poorthuis Ate
Published: August 2021

‘Village’ as a metaphor, propelled by mobilizing nostalgia for the ‘rural’ as counter to urban fragmentation, has been used across nations to engender a sense of place and community in urban spaces. In Singapore, the narrative of kampung (Malay for village), rooted in restorative nostalgia, has been used repeatedly to foster living in harmony. However, it remains unclear in what ways ‘kampung’ and related social policies resonate with current citizens. The main objective of this research is to generate a grounded, interpretive lens on the term kampung to better understand its meaning and relevance in the context of urban living. A mixed methods approach comprising discourse analysis, in‐depth interviews and Q‐methodology was used to engage a diverse group of residents in generating grounded perspectives around the construct. We show ‘kampung’ is a heterogenous concept that can be understood through five analytically distinct perspectives wherein race, place, neighbouring, and personal agency vis‐à‐vis the role of government are recurring themes. The findings lend a social constructivist perspective to wider geographical debates around the urban/rural dichotomy and outline some possibilities for ‘kampung’ under present conditions.
To Follow the Prescribed Pathway? Aspiring Professional Women and Anticipations of Work–Family Conflict1
Authors: Hummer Holly
Published: August 2021

Women have made rapid progress in the professional arena yet numerous studies document how issues of work–family conflict continue to disproportionately affect women’s careers. This paper asks if and how anticipations of work–family conflict emerge in aspiring professional women’s career decision‐making processes before they enter the labor market and further, how these anticipations shape career‐relevant decisions. Using interview data with 43 women students at two universities in MBA, JD, and PhD programs as a case study of aspiring professional women, I find that students in graduate programs feel channeled toward “prescribed pathways,” or normalized, high‐status career paths. At the same time, women students come to view these pathways as the most susceptible to work–family conflict while they frame other, less institutionally normalized pathways as more suitable for balancing with family life. Using data on interviewees’ real job decisions, I then outline three distinct ways in which women’s views regarding future work–family conflict translate into career choices, arguing that seemingly gender‐neutral professionalization contexts such as graduate school impact how women come to view certain career paths as more or less family‐friendly and relatedly, their subsequent short and long‐term career‐relevant decisions.
Meeting the Moral Markers of Success: Concerted Cultivation among Second‐Generation Muslim Parents*
Authors: Karam Rebecca A.
Published: August 2021

Concerted cultivation describes how parents reproduce middle‐class status by preparing children for success through the organization of their family’s daily lives. Scholarship accounting for the potentially important role that minority religious identity plays in this process is warranted. The current study fills this theoretical and empirical niche by exploring the parenting practices of second‐generation, upper‐middle‐class Muslim Americans. I show how within the context of rising Islamophobia, members of this group defined success for their children using both socioeconomic markers and moral markers, in which Islam and excellent character traits are crucial. With this definition in mind, parents aimed to reproduce both class and religion in the third generation using concerted cultivation strategies. I utilize data from two years of ethnographic fieldwork and 72 in‐depth interviews with second‐generation Arab and South Asian Muslim Americans in suburban Metro‐Detroit. I make contributions to sociology by presenting novel data on a little understood minority group and their institutions and by bringing religion into discussions of second‐generation parenting styles and class reproduction.
The COVID‐19 pandemic and the search for structure: Social media and conspiracy theories
Authors: Dow Benjamin J. , Johnson Amber L. , Wang Cynthia S. , Whitson Jennifer , Menon Tanya
Published: August 2021

The study outlines a model for how the COVID‐19 pandemic has uniquely exacerbated the propagation of conspiracy beliefs and subsequent harmful behaviors. The pandemic has led to widespread disruption of cognitive and social structures. As people face these disruptions they turn online seeking alternative cognitive and social structures. Once there, social media radicalizes beliefs, increasing contagion (rapid spread) and stickiness (resistance to change) of conspiracy theories. As conspiracy theories are reinforced in online communities, social norms develop, translating conspiracy beliefs into real‐world action. These real‐world exchanges are then posted back on social media, where they are further reinforced and amplified, and the cycle continues. In the broader population, this process draws attention to conspiracy theories and those who confidently espouse them. This attention can drive perceptions that conspiracy beliefs are less fringe and more popular, potentially normalizing such beliefs for the mainstream. We conclude by considering interventions and future research to address this seemingly intractable problem.
Considerações Acerca de um Xenólito Ocorrente em Corpo Ultrabásico de Liberdade, MG
Authors: Souza Maria Suzana Pessoa de , Zalán Pedro Victor
Published: August 2021

This work describes a rock found as a xenolith in an ultrabasic body of serpentinite, situated in the vicinity of Liberdade, south of the State of Minas Gerais. Its mineralogical assemblage is predominantly composed of andradite, followed by hornblende and quartz, having zircon, kyanite and zoisite as accessory minerals. It is thought that such rock represents an equilibrium assemblage in a transitional facies, probably between the eclogite and amphibolite facies.
Paleoclimatologia dos Depósitos Continentais Cenozóicos da Bacia de Resende
Authors: Amador Elmo Da Silva
Published: August 2021

An examination of mineralogical data together with textural and structural aspects, from Cenozoic con tinental sediments of the Resende Basin, middle Paraiba river Valley (Rio de Janeiro, Brazil) provide some considerations about paleoclimatology in relation to deposition and source area. Based on predominance of the montmorillonite clay mineral group, unstable heavy mineral assemblage and fresh roudness feldspar contents in the deposits, the lower unit, Resende Formation, Miocene to Pliocene in age, is interpreted as deposited in semiarid climatic conditions. It is suggested that there has been a predominance of mechanical morphogenetic processes and a poor chemical weathering in the source area. The dry period recorded in the Resende Formation is related to the begginning of a extensive glaciation that covered the Antartic Continent with massive ice Sheets according to Jacobs (1974) and others and initiated prior to the late Miocene. On the other hand, the base of similar correlated formations in the brasilian coastal plain are presently found at 80 m. to 100 m. below sea level (Alexandra and Graxaim Formations). In Pliocene/Pleistocene boundary time the climate changed to a humidic type. The Fleistocene period shows great climatic instability and its interpretation is still a mather of dispute. According to Bigarella et al (1965 b) the pleistocenic sedimentary formations indicate an alternating climatic cycle caused mainly by periods of extreme climatic changes from humid to semiarid and from warm to cold. Other authors have considered such brazilian cenozoic sedimentations as related to humid climates (Almeida, 1965 and Wernick, 1966). It is not the purpose of this paper to settle all arguments on this controversial subject. Moreover, the present results of mineralogical data suggest that the Upper Formation (Floriano Fm) exhibited climatic conditions that probably changed between humid to semi-humid.
Fatores Geradores de Fluxos Aéreos de Passageiros: Uma Abordagem Preliminar
Authors: Freire Lucy A. R. , Sant'Anna Marina
Published: August 2021

The purpose of this article is to present the results of a study of interurban air travel in Brazil. The work was developed by looking for the principal factors that influence the number of passengers who travel between a specified pair of cities in a particular period of time. The results revealed that the volume of passengers is strongly related to city size and tenuosly related to income, distance and population occupation. Finally, the results revealed also that although all variable influence air passenger potential,the relative Importance of each variable differs from city to city.
Distribuição de Invertebrados Marinhos na Planície Costeira do Rio São João, eEtado do Rio de Janeiro
Authors: Brito Ignacio Aureliano Machado , Carvalho Maria Da Gloria Pires de
Published: August 2021

A study of the distribution of macrofauna and the ecological factors affecting their distribution in the São João coastal plain, State of Rio de Janeiro, has made it possible to formulate a series of criteria for interpreting modern and ancient depositional environments. In all the extension of the area there are uncontestable records of ancient sea - levels higher than the present. During the Flandrean transgression the sea reached the foot of the Precambrian crystalline rocks along the entire coastline of the studied area. Different assemblages were recognized in the São João coastal plain such as shallow hypersaline, open lagoon, closed lagoon and river influenced low salinity estuary.
Dimensão Temporal e Sistemas Espaciais no Terceiro Mundo
Authors: Santos Milton
Published: August 2021

This paper deals essentially with the importance of the temporal dimension in analytical considerations of space. The notion of "space" is in fact inseparable from the notion of 'systems of time' At any given moment in local, regional, national, or world history, the action of different variables depends upon prevailing conditions in the corresponding temporal system. Consequently, any one variable can only be considered within the system to which it belongs, since its significance changes along time. Likewise, no variable can be considered alone, given that space is the result of the geographical arrangement of a set of variables and of their localized interaction. Moreover, the succession of temporal systems, corresponding on a world scale to historical periods,coincides with the succession of modernizations. The latter can be divided into five distinct periods and this periodization can be used not only to explain spacial distribution patterns of the most varied events, but also to provide the key to understanding place to place difierences within the underdeveloped world.
Microstructure Alteration in the High-Speed Machining of Titanium Alloy Involved With Tool Wear and Cryogenic Condition
Authors: Li Xin , Zhang Xueping , Shivpuri Rajiv
Published: August 2021

The microstructure alteration generated in the high-speed machining of titanium alloy has significant influence on the performance, quality and service life of production. The prediction of grain size or phase distribution based on physics mechanism or the regression of experimental data have been reported in the process of static or quasi-static state. However, it is still a challenge to predict the phase transformation and grain growth process in machining accurately and effectively since it has characteristics of high strain, strain rate and temperature. In this paper, a novel FEM-based model involving with the microstructure alteration was introduced and implemented to predict finial grain size or phase result in the high-speed machining of Ti-6Al-4V alloys especially at the machined surface. The phase transformation process was proposed and discussed by considering tool wear and cryogenic condition at machined surface, while the microstructure results were displayed on the chip in the previous works. Firstly, the phase volume fraction and grain size were modelled by experimental data. Then the simulation based on the self-consistent method (SCM) was used to output strain and temperature distribution. Thirdly, the phase volume fraction and grain size expressions were transmitted into subroutine programs and the microstructure alteration process under the different cutting conditions were showed in the FE results. The simulation results of temperature, phase fraction and strain were compared against previous simulation or experiment results in published papers revealing good agreement. The proposed model was further to investigate the influence of tool wear and cutting temperature on machined surface. The results indicated that the tool wear increased heat at the flank face significantly resulting to β phase increasing and grain growth at machined surface and the cryogenic condition would lower temperature gradient as well as stress gradient contributing to reduce roughness and residual stress.
Ultrasonic Vibration-Assisted Laser Directed Energy Deposition of B4C-Ti Composite: Effect of Laser Power and Ultrasonic Vibration
Authors: Li Yunze , Zhang Dongzhe , Cong Weilong
Published: August 2021

Compared with pure titanium, ceramic reinforced titanium matrix composites (TMCs) have the advantages of higher microhardness, higher wear resistance, and better load endurance properties, which enable their further applications under severe friction and cyclic loading conditions. B4C-Ti composite, as a kind of TMCs, has been fabricated by laser directed energy deposition (DED) technology. However, there are still some problems needed to be solved. First, the B4C particles are not fully melted. It suppresses the reactions between B4C and titanium and reduced the generation of TiB and TiC during the fabrication, which deteriorates the hardness of the B4C-Ti composite. Second, the reinforcement materials are not evenly distributed in the titanium matrix, which damages the performance of the B4C-Ti composite. In this study, B4C-Ti composite parts are fabricated by the ultrasonic vibration-assisted laser DED process. The effects of laser power and ultrasonic vibration on the phase compositions, microstructure, and hardness are investigated.
Investigating Optimal Parameter Combination for Friction Stir Spot Welding on AL7075-T6: Engineering Robust Design Approach
Authors: Jakobsen Jan-Tore , Ratnayake R. M. Chandima , Sætre Sem Sølve , Neverdal Arnfinn
Published: August 2021

Friction stir spot welding (FSSW) is a solid-state joining technique which is used to weld alloys that has a low weldability such as the 2000 and 7000 series aluminum alloy. The marine, automotive and aerospace industry benefits using this method as the need for weight reduction and fuel economy make the use of aluminum and other light metals necessary. The purpose of this study is to find the optimum parameters and the ultimate failure load for FSSW welded specimens in a basic lap configuration. Two coupons of AA7075-T6 with a dimension of 210 × 30 × 0.8 mm and 210 × 30 × 1.6 mm were welded using a self-made FSSW machine rebuild for the purpose of this project. The experiment was performed using engineering robust design approach to investigate the optimal parameter combinations that provides optimal joint performance. Experiments has been carried out using the Taguchi L9 orthogonal arrays with 4 factors and 3 levels. The factors and levels were chosen as follows: pin length in the interwall 1.2 mm to 1.6 mm, shoulder depth 0 to 0.4 mm, dwell time 1 sec to 2.5 sec and tool rotation speed 1800 rpm to 2600 rpm. The joint performance has been evaluated considering the ultimate tensile load. Tensile testing of weldments was carried out using an Instron Universal Testing Machine. To estimate the error variance for the factor effects and variance of the predicted error analysis of variance (ANOVA) was performed. The mathematical framework anticipated an ultimate failure load of 3286N, and the verification run confirmed the predicted result by an average of 3215N. The optimum parameters were found to be a pin length of 1.4 mm, shoulder depth of 0.4 mm, dwell time at 2.5 sec and a rotational speed of 2200 RPM. The ANOVA showed that the shoulder depth was the dominant factor influencing 87.9 % of the variation of the signal-to-noise ratio (S/N).
Predicting Nugget Size of Resistance Spot Welds Using Infrared Thermal Videos With Image Segmentation and Convolutional Neural Network
Authors: Guo Shenghan , Wang Dali , Chen Jian , Feng Zhili , Guo Weihong “Grace”
Published: August 2021

Resistance spot welding (RSW) is a widely adopted joining technique in automotive industry. Recent advancement in sensing technology makes it possible to collect thermal videos of the weld nugget during RSW using an infrared camera. The effective and timely analysis of such thermal videos has the potential of enabling in-situ nondestructive evaluation (NDE) of the weld nugget by predicting nugget thickness and diameter. Deep learning (DL) has demonstrated to be effective in analyzing imaging data in many applications. However, the thermal videos in RSW present unique data-level challenges that compromise the effectiveness of most pre-trained DL models. We propose a novel image segmentation method for handling the RSW thermal videos to improve the prediction performance of DL models in RSW. The proposed method transforms raw thermal videos into spatial-temporal instances in four steps: video-wise normalization, removal of uninformative images, watershed segmentation, and spatial-temporal instance construction. The extracted spatial-temporal instances serve as the input data for training a DL-based NDE model. The proposed method is able to extract high-quality data with spatial-temporal correlations in the thermal videos, while being robust to the impact of unknown surface emissivity. Our case studies demonstrate that the proposed method achieves better prediction of nugget thickness and diameter than predicting without the transformation.
Thermal Monitoring and Modeling of Ti-6Al-4V Thin Wall Temperature Distribution During Blown Powder Laser Directed Energy Deposition
Authors: Paudel Basil J. , Marshall Garrett J. , Thompson Scott M.
Published: August 2021

The effects of Ti-6Al-4V part size on its temperature distribution during the blown-powder directed energy deposition-laser (DED-L) process was investigated through dual-thermographic monitoring and a unique modeling technique. Results demonstrate that the duration of dwell times are a significant contributing factor affecting the rate at which a steady-state temperature field is achieved. Longer walls took significantly more layers/time to achieve a uniform temperature profile. Maximum and average melt pool temperatures appear to be near independent of part size at a steady state. Finite element simulation results show that a quasi-steady melt pool temperature may be unique to a layer, especially for layers near the substrate. Layer-wise steady melt pool temperatures were achieved within the first few seconds of track scanning. A proposed fin modeling-based temperature distribution was found to predict the thermal profile in a ‘substrate affected zone’ (SAZ) along the scan direction within 5%. A method to predict the onset of the SAZ has also been proposed. Process parameters used for the DED-L of component volumes are not necessarily optimal for thin-walled structures due to their significantly lower thermal capacity.
Photodiode-Based In-Process Monitoring of Part-to-Part Gap and Weld Penetration Depth in Remote Laser Welding of Copper-to-Steel Battery Tab Connectors
Authors: Chianese Giovanni , Franciosa Pasquale , Nolte Jonas , Ceglarek Darek , Patalano Stanislao
Published: August 2021

This paper addresses in-process monitoring of part-to-part gap and weld penetration depth using photodiode-based signals during Remote Laser Welding (RLW) of battery tab connectors. Photodiode-based monitoring has been largely implemented for structural welds due to its relatively low cost and ease of automation. However, the application of photodiode-based monitoring to RLW of thin foils of dissimilar metals for battery tab connectors remains an unexplored area of research and will be addressed in this paper. Motivated by the high variability during the welding process of thin foils of dissimilar metals, this paper aims to evaluate the photodiode-based signals to determine if variations in weld quality can be isolated and diagnosed. The main focus is in diagnosing defective weld conditions caused by part-to-part gap variations and/or excessive weld penetration depth. Photodiode-based signals have been collected during RLW of copper-to-steel thin foils lap joint (Ni-plated copper 300 μm to Ni-plated steel 300 μm). The methodology is based on the evaluation of the energy intensity and scatter level of the signals. The energy intensity gives information about the amount of radiation emitted during the welding process, and the scatter level is associated to the accumulated and un-controlled variations. Findings indicated that part-to-part gap variations can be diagnosed by observing the step-change in the plasma signal, with no significant contribution given by the back-reflection. Results further suggested that over-penetration corresponds to significant increment of the scatter level in the sensor signals. Opportunities for automatic isolation and diagnosis of defective welds based on supervised machine learning will be discussed throughout the paper.
Parametric Control of Melting Gel Morphology and Chemistry via Electrospray Deposition
Authors: Grzenda Michael , Gamboa Arielle , Mercado James , Lei Lin , Guzman Jennifer , Klein Lisa C. , Jitianu Andrei , Singer Jonathan P.
Published: August 2021

Melting gels are a class of hybrid organic-inorganic, silica-based sol-gels which are solid below their glass transition temperatures, near room temperature, but show thermoplastic behavior when heated. While this phase change can be repeated multiple times, heating the gel past its consolidation temperature, typically above 130 °C, initiates an irreversible reaction that produces highly crosslinked glassy organic/inorganic materials via hydrolysis and polycondensation. This ability makes melting gels uniquely compatible with processing techniques inaccessible to other sol-gels. By properly tuning their properties, it should be possible to create protective coatings for electronics and anti-corrosive coatings for metals that are highly hydrophobic and insulating. However, melting gel consolidation reactions are highly dependent on charge interactions, raising the question of how these materials will respond to a processing technique, like electrospray deposition (ESD), which is dependent on charge delivery. In this study, we focus on the role that substrate temperature and charge polarity play on film morphology, consolidation chemistry, and surface properties when processing via ESD. Optical images, film thickness measurements, and FTIR were used to characterize the sprayed melting gel with the goal of developing a robust processing space for producing highly cross linked, hydrophobic, dielectric coatings.
Tool Wear Analysis of MTConnect Production Data
Authors: Stock David , Mukhopadhyay Aditi , Potter Rob , Henderson Andy
Published: August 2021

This paper presents the analysis of data collected using the MTConnect protocol from a lathe with a Computer Numerical Control (CNC). The purpose of the analysis is to determine an estimated cutting tool life and generate a model for calculating a real-time proxy of cutting tool wear. Various streams were used like spindle load, NC program blocks, the mode, execution etc. The novelty of this approach is that no information about the machining process, beyond the data provided by the machine, was necessary to determine the tool’s expected life. This method relies on the facts that a) it is generally accepted cutting loads increase with tool wear and b) that many CNC machines rely on a small set of regularly run CNC programs. These facts are leveraged to extract the total load for each run of each program on the machine, creating a dataset which is a good indicator of tool wear and replacement. The presented methodology has four key steps: extracting cycle metadata from the machine execution data; computing the integrated spindle loads for every cycle; normalizing the integrated spindle loads between different programs; extracting tool wear rates and changes from the resulting dataset. It is shown that the method can successfully extract the signature of tool wear under a common set of circumstances which are discussed in detail.
Investigation of the Functional Properties of Additively-Fabricated Triply Periodic Minimal Surface-Based Bone Scaffolds for the Treatment of Osseous Fractures
Authors: Chaffins Abigail , Yu Mohan , Claudio Pier Paolo , Day James B. , Salary Roozbeh (Ross)
Published: August 2021

Fused deposition modeling (FDM), is a direct-write material extrusion additive manufacturing process, which has emerged as a method of choice for the fabrication of a wide range of biological tissues and structures. FDM allows for non-contact, multi-material deposition of a broad spectrum of functional materials for tissue engineering applications. However, the FDM process is intrinsically complex, consisting of a multitude of parameters as well as material-machine interactions, which may adversely influence the mechanical properties, the surface morphology, and ultimately the functional integrity of fabricated bone scaffolds. Hence, process optimization in addition to physics-based characterization of the FDM process would be inevitably a need.

The overarching goal of this research work is to fabricate biocompatible, porous bone scaffolds, incorporating autologous human bone marrow mesenchymal stem cells (hBMSCs), for the treatment of osseous fractures, defects, and eventually diseases. The objective of this work is to investigate the mechanical properties of several triply periodic minimal surface (TPMS) bone scaffolds, fabricated using fused deposition modeling (FDM) additive manufacturing process.

In this study, biocompatible TPMS bone scaffolds were FDM-deposited, based on a medical-grade polymer composite, composed of polyamide, polyolefin, and cellulose fibers (named PAPC-II). In addition, the experimental characterization of the TPMS bone scaffolds was on the basis of a single factor experiment. The compression properties of the fabricated bone scaffolds were measured using a compression testing machine. Furthermore, a digital image processing program was developed in the MATLAB environment to characterize the morphological properties of the fabricated bone scaffolds.
A Semi-Supervised Multiclass Anomaly Detection Approach for Partially Labeled In-Process Measurement Data
Authors: Cohen Joseph , Ni Jun
Published: August 2021

Machine learning and other data-driven methods have developed at a prolific rate for industrial applications due to the advent of industrial big data. However, industrial datasets may not be especially well-suited to supervised learning approaches that require extensive domain knowledge in the complete and accurate labeling of datasets. To address these challenges, a semi-supervised learning approach is proposed that makes use of partially labeled subsets. The proposed methodology is applied to high-dimensional in-process measurement data, utilizing a convolutional autoencoder for unsupervised feature extraction. A multiclass extension for semi-supervised anomaly diagnosis is proposed that utilizes principal component analysis as the basis for anomaly scoring, and the proposed approach intersects the results of targeted one-against-all phases on partially labeled sets to classify faults. Experiments in a case study on semiconductor manufacturing measurement data are performed to explore the relationship between latent features extracted and anomaly detection performance. The application of the proposed algorithm achieves a true positive detection rate of over 90% with false positive rate under 9% for both local and global anomaly types, with these results accomplished while reducing over 99% of the original input data dimensions. In addition, the approach also allows for positive samples to be identified that were previously undetected by human experts. These results are promising for the application of the proposed semi-supervised methodology in real industrial settings.
Predictions of Cutting Force and Tool Wear in Gear Power Skiving
Authors: Ren Zongwei , Fang Zhenglong , Arakane Takuhiro , Kizaki Toru , Feng Yannan , Nishikawa Tsukasa , Kugo Junshi , Nabata Eiji , Sugita Naohiko
Published: August 2021

Power skiving is a promising method that can enhance the efficiency of gear machining. The machining mechanism is complicated due to several factors, such as the continuous variation in the rake angle and undeformed chip thickness. The tool wear process is also difficult to be evaluated due to the constantly varying in cutting conditions. Hence, to make a comprehensive understanding of the cutting process, we proposed a parametric modeling process based on the kinematics of power skiving. In this model, the undeformed cutting chip was calculated in each pass and shows the consistency with deformed cutting chip in experiments. The effective rake angle and undeformed cutting chip thickness were defined, calculated, and displayed on undeformed cutting chip for a better understanding of the cutting process. The cutting force and tool crater wear were calculated by estimating the distribution of the stress and temperature on the rake face of the cutting tool. Multiple radial-feed experimental evaluations were conducted with the gears of construction vehicles. In the results, the predicted margin of the absolute error of the normal force on the rake face was under 5% in every pass. The wear distribution on the rake face is consistent with the superimposed tool-chip contact area. The results show high potential for the optimization of the cutting tool or cutting conditions in gear power skiving.
Framework for User-Friendly Modeling of Energy Use in Fused Deposition Modeling
Authors: Wang Xiange , Kent Philip , Linke Barbara S.
Published: August 2021

Additive manufacturing has experienced rapid growth in recent years due to its advantage of producing less waste and prototyping at a faster rate compared to traditional manufacturing. As the demand for customized and rapidly manufactured parts continues to expand, in particular Fused Deposition Modeling (FDM) as an easily accessible process has been growing significantly. A lot of research in this area focuses on improving the print part surface roughness and dimensional accuracy, but there is a lack of in-depth analysis on the environmental impact and energy consumption of FDM machines as well as on user-friendly energy models. This paper offers a review of selected efforts on modeling energy consumption through physics-based methods as well as on empirical methods and proposes a framework structure for energy modeling targeted towards user-friendliness and transparency. The user should be able to improve FDM efficiency in the form of energy and/or time efficiency, gain understanding of printer energy consumption and obtain recommendations for printer setting and usage. A Graphic User Interface of the model and a model design structure are proposed in this work along with useful analytical equations and methods. Modeling of waste heat and inclusion of part quality are further features of the suggested energy model framework.
A Study of the Efficacy of Flame Electrical Resistance for Standoff Measurements During the Oxyfuel Cutting Process
Authors: Martin Christopher R. , Untaroiu Alexandrina , Xu Kemu , Rahman S. M. Mahbobur
Published: August 2021

This is a study of the suitability of preheat flame electrical resistance as a potential method for measuring the standoff distance an oxyfuel cutting torch and a work piece. Careful scrutiny of forty seven (47) individual experiments demonstrate that when cut quality is good, there is a linear repeatable relationship between the two with uncertainty about ± .3mm (.015in). As the cut quality degrades, the formation of top-edge dross reduces the electrical path length in the flame, and momentary reduction in the reaction rate in the kerf reduces the free electrons in the flame, causing rises in flame resistance. In these conditions, measurement uncertainty reduces to ± 1mm (.040in) or worse.
Impacts of Process Parameters on Shape Memory Properties of Stereolithography Manufactured Parts: An Experimental Analysis
Authors: Zhao Jing , Han Muyue , Li Lin
Published: August 2021

The emergence of smart materials coupled with additive manufacturing technology has provided competitive advantages over traditional manufacturing systems in terms of manufacturing flexibility, product functionality, and the ability to switch between multiple phases under given external stimuli. Although the fabricability of shape memory materials has been widely explored in stereolithography systems, the shape memory performance of printed smart structures has not been extensively studied. More specifically, in current literature, the printing process is mainly considered independent of material characteristics, and a lack of information is reported on how the printing parameters affect the shape fixity and free recovery performance of the printed parts. Therefore, this work is dedicated to experimentally investigating the influences of parameters from both the stereolithography printing process and thermomechanical process (i.e., shape programming and free recovery) on the shape memory properties. Five parameters, including layer thickness, scan speed, maximum programmed angle, hold time, and recovery time, are experimentally analyzed for their impacts on the shape morphing capabilities. According to the results of this study, a variation of 14.33% on the free recovery ratio can be observed when the scan speed is altered. In addition, the printing process parameters exhibit high levels of dominance in affecting the shape memory performance over parameters involved in the thermomechanical process, such as hold time and maximum programmed angle.
Precision Evaluation of NeXus, a Custom Multi-Robot System for Microsystem Integration
Authors: Wei Danming , Tofangchi Alireza , Sherehiy Andriy , Saadatzi Mohammad Hossein , Alqatamin Moath , Hsu Keng , Popa Dan O.
Published: August 2021

Industrial robots, as mature and high-efficient equipment, have been applied to various fields, such as vehicle manufacturing, product packaging, painting, welding, and medical surgery. Most industrial robots are only operating in their own workspace, in other words, they are floor-mounted at the fixed locations. Just some industrial robots are wall-mounted on one linear rail based on the applications. Sometimes, industrial robots are ceiling-mounted on an X-Y gantry to perform upside-down manipulation tasks. The main objective of this paper is to describe the NeXus, a custom robotic system that has been designed for precision microsystem integration tasks with such a gantry. The system tasks include assembly, bonding, and 3D printing of sensor arrays, solar cells, and microrobotic prototypes. The NeXus consists of a custom designed frame, providing structural rigidity, a large overhead X-Y gantry carrying a 6 degrees of freedom industrial robot, and several other precision positioners and processes. We focus here on the design and precision evaluation of the overhead ceiling-mounted industrial robot of NeXus and its supporting frame. We first simulated the behavior of the frame using Finite Element Analysis (FEA), then experimentally evaluated the pose repeatability of the robot end-effector using three different types of sensors. Results verify that the performance objectives of the design are achieved.
Anisotropic Cutting Force Characteristics in Milling of Maraging Steel Processed Through Selective Laser Melting
Authors: Tamura Shoichi , Matsumura Takashi , Ezura Atsushi , Mori Kazuo
Published: August 2021

Additive manufacturing process of maraging steel has been studied for high value parts in aerospace and automotive industries. The hybrid additive / subtractive manufacturing is effective to achieve tight tolerances and surface finishes. The additive process induces anisotropic mechanical properties of maraging steel, which depends on the laser scanning direction. Because anisotropy in the workpiece material has an influence on the cutting process, the surface finish and the dimension accuracy change according to the direction of the cutter feed with respect to the laser scanning direction. Therefore, the cutting parameters should be determined to control the cutting force considering material anisotropy. The paper discusses the cutting force in milling of maraging steel stacked with selective laser melting, as an additive manufacturing process. Anisotropic effect on the cutting forces is proved with the changing rate of the cutting force in milling of the workpieces stacked by repeating laser scanning at 0/90 degrees and 45/−45 degrees. The cutting forces, then, are analyzed in the chip flow models with piling up of orthogonal cuttings. The force model associates anisotropy with the shear stress on the shear plane. The changes in the cutting forces with the feed direction are discussed in the cutting tests and analysis.
Hybrid-Light-Source Stereolithography for Fabricating Macro-Objects With Micro-Textures
Authors: Jia Wenxuan , Leung Yuen-Shan , Mao Huachao , Xu Han , Zhou Chi , Chen Yong
Published: August 2021

Microscale surface structures are commonly found on macroscale bodies of natural creatures for their unique functions. However, it is difficult to fabricate such multi-scale geometry with conventional stereolithography processes that rely on either laser or digital micromirror device (DMD). More specifically, the DMD-based mask projection method displays the image of a cross-section of the part on the resin to fabricate the entire layer efficiently; however, its display resolution is limited by the building area. In comparison, the laser-based vector scanning method builds smooth features using a focused laser beam with desired beam-width resolution; however, it has less throughput for its sequential nature. In this paper, we studied the hybrid-light-source stereolithography process that integrates both optical light sources to facilitate the fabrication of macro-objects with microscale surface structures (called micro-textures in the paper). The hardware system uses a novel calibration approach that ensures pixel-level dimensional accuracy across the two light sources. The software system enables designing the distribution and density of specific microscale textures on a macro-object by generating projection images and laser toolpaths for the two integrated light sources. Several test cases were fabricated to demonstrate the capability of the developed process. A large fabrication area (76.8 mm × 80.0 mm) with 50 μm micro-features can be achieved with a high throughput.
Design and Manufacturing of Topology Optimized Heat Sinks Made of Copper Using 3D Printing
Authors: Taha Bilal , Patil Sandeep , Dennis Brian H.
Published: August 2021

The performance of a heat sink is highly dependent on the overall surface area available for convective heat transfer. Topology optimization technique has widely been used to achieve complex thermal designs which are more compact in size and have larger surface areas. In addition to it, the optimized heat sink designs are much lighter and have reduced mass compared to conventional designs. Conventionally thermal topology optimization is performed using numerical analysis which considers both conduction and convection process coupled together. The authors in this paper have presented a simple and a novel methodology for performing thermal topology optimization of heats sinks using ANSYS workbench software. To manufacture the complex design of the heat sink, Fused Filament Fabrication technique commonly known as 3D printing process was used. Virtual Foundry’s Copper-PLA filament having 90% copper and 10% PLA material was used as the primary material of choice. Furthermore, to achieve a heat sink made purely of copper, sintering process of the 3D-printed part was carried out in a vacuum furnace. The optimized design proved to be more thermally efficient and compact in size whereas the manufacturing technique used demonstrated quite an economical way of producing such complex topology optimized designs for heat sinks.
Vibration-Assisted Insertion of Flexible Neural Microelectrodes With Bio-Dissolvable Guides for Medical Implantation
Authors: Wang Yi , Shih Yen Yu Ian , Lee Yuan-shin
Published: August 2021

This paper presents vibration-assisted insertion of flexible neural electrodes with bio-dissolvable guides to deliver accurate microprobe insertion with minimized tissue damage. Invasive flexible neural microprobe is an important new tool for neuromodulation and recording research for medical neurology treatment applications. Flexible neural electrode probes are susceptible to bending and buckling during surgical implantation due to the thin and flexible soft substrates. Inspired by insects in nature, a vibration-assisted insertion technique is developed for flexible neural electrode insertion to deliver accurate microprobe insertion with minimized tissue damage. A three-dimensional combined longitudinal-twisting (L&T) vibration is used to reduce the insertion friction force, and thus reducing soft tissue damage. To reduce the flexible microelectrode buckling during surgical insertion, a bio-dissolvable Polyethylene glycol (PEG) guide is developed for the enhancement of flexible neural probe stiffness. Combining these two methods, the insertion performance of the flexible neural probe is significantly improved. Both the in vitro and the in vivo experiments were conducted to validate the proposed techniques.
Integrating Friction-Stir Back Extrusion to Powder Metallurgy
Authors: Dhoka Sahil , Wagner Scott W. , Abhi Himansshu , Hendrickson Nicholas V. , Emblom William J.
Published: August 2021

Reducing fuel consumption has been a driving factor for researchers and manufacturers to continually develop improved methods for reducing the weight of automobiles or lightweighting. These vehicle lightweighting demands have directed researchers to look to using materials that are typically more difficult to manufacture in their studies. As a result, friction stir processing techniques are being looked at more closely. There are advantages to using friction stir methods. Dissimilar metals can be welded and fine-grained products can be created using friction stir methods to name a few. It can be an ideal solution for manufacturing high-conductive metals and alloys. Foamed aluminum tube similar to the one shown by Yoshiko Hangai et al [1] can be formed using the proposed process which could be used to develop lightweight automobile components.

This paper provides preliminary results and insights gained when fine metal powders were used in a friction stir back extrusion (FSBE) setup. The tooling consisted of a D2 tool steel die with an H13 rotating probe mounted in a CNC mill. Within the die, commercially pure aluminum powder was topped by an aluminum cap with a milled pocket in the center. This pocket was used to locate the spin tool in the center of the cap and reduce the potential for the tool to drift and deflect. The cap was also used for compacting the powdered aluminum. X-ray diffraction indicated that Al13Fe4 was formed, indicating that the temperature within the die reached a minimum of 800°C and also indicated that the powder had the potential to partially sinter and melt.
Characterization of Co-Cr-Mo Alloys Manufacturing via Directed Energy Deposition
Authors: Liu Michael , Kuttolamadom Mathew
Published: August 2021

In this study, Co-Cr-Mo samples that were fabricated via directed energy deposition (DED) at various laser powers and powder feed rates were characterized to ascertain their microstructure and mechanical properties. Co-Cr-Mo is a common alloy for total hip and knee replacements, dental, and support structures due to its biocompatibility, hardness and abrasion resistance, making them a preferred alloy for metal-on-metal (MOM) contact. This study was undertaken to understand the pertinent process parameters that would generate structurally viable bulk structures. High-resolution microscopy and spectroscopy revealed the presence of networked and jagged carbides with varying amounts of Mo. Further, XRD confirmed the presence of the γ and ε phases. Micro- and nano-scale characterization of the alloy fabricated at different process conditions showed material properties in line with those made via traditional processing approaches such as casting. Altogether, this investigation provided an understanding of the effect of additive manufacturing process parameters on the microstructure and properties of Co-Cr-Mo.
Effects of Size Reduction on the Failure Mechanism of 3D Printed PLA+ Parts
Authors: Decker Zane , Makulinski Mason , Vispute Suprita , Sundaram Murali
Published: August 2021

Fused Deposition Modeling (FDM) with Poly(lactic Acid) plus (PLA+) is frequently used in rapid prototyping and 3D printing of complex shapes. Owing to their light weight, manufacturability and cost effectiveness, thermoplastic parts made by FDM are increasingly used in several applications ranging from tissue engineering to consumer goods industry. Understanding the size effects on the strength of these parts is essential to extend their use in the microsystem applications. This paper studies the effect of scale on the mechanical properties and failure mechanisms of a 3D printed parts made by FDM. Process parameter such as extrusion temperature, infill density, infill pattern, print speed, layer thickness and nozzle diameter were kept consistent for this experiment. Five samples each with a square cross-sectional area of side lengths of 2mm, 4mm, 6mm, and 10mm were subjected to a tensile test. It was observed that parts with a smaller cross-sectional area experienced ductile failure as opposed to brittle fracture in larger cross-sectional area. Failure is shown to occur at sections where the geometry changes for brittle fractures while it occurs at the center of the parts displaying ductile failure. Results of the tensile test show a non-uniform ultimate yield strength across the four sizes. Crystallization of the material due to nozzle temperature at extrusion could be a contributing factor to failure discrepancies. Increase in the cycle time is theorized to improve the layer to layer adhesion of the part thereby affecting its mode of failure.
Investigation of the Dynamic Response of a Multispot System at Joining Using Ultrasonic Welding
Authors: Lee Tae Hwa , Wang Pei-Chung , Hu S. Jack , Banu Mihaela
Published: August 2021

Ultrasonic welding is one of the most practical joining method for polymer composite materials and has been adapted in the aerospace and automotive industries. To effectively join polymer composite assemblies, it is critical to understand the dynamic response of the welding system so that sound heating generation and welding sequences in the ultrasonic welding of the assemblies can be properly obtained. This study presents a dynamic response model of a multi-spot configuration assembly using ultrasonic welding. Here, a dynamic model of joining a U-shaped carbon fiber reinforced thermoplastic composite part with a flat part is developed and analyzed through the ratio between the frequencies generated at different locations of the spot with respect to the edges of the assembly and the natural frequency. Finally, this ratio is correlated with the weld quality of the multiple spot configuration. Guidelines for designing multisport sequence are extracted. This study provides a method to design the welding sequence in ultrasonic welding of carbon fiber reinforced composites.