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2023 research outputs found
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msamDB: Towards addressing data-scarcity challenges in L-PBF additive manufacturing
No full textData science techniques, particularly machine learning (ML), have proven to be valuable tools in PBF-LM research. While ML can rapidly model the large process parameter space of PBF-LM, their efficacy is dependent on large, informative and diverse training datasets. However, scarcity in the development and availability of such datasets is an on-going challenge. This work outlines the on-going progress to address this challenge through the development of a database platform, tentatively named msamDB (multi-scale additive manufacturing database). This platform, specifically created to manage PBF-LM academic research data, is a modular, extensible and scalable database that can promote data-sharing among researchers. The initial architecture of msamDB focuses on surface roughness data generated throughout the PBF-LM lifecycle. This work highlights the findings and challenges encountered in the design, implementation and pilot data population stages of msamDB. In its current stage, msamDB data spans data from approximately 30 builds, multiple research and industry studies, 3 different powder materials and a broad range of process parameters. Data has been collected from various stages such as powder characterization, build planning, process parameter selection, surface characterization, etc. In reference to surface roughness measurements, the database currently has more than 1000 data points across various surface orientations. This work represents first known effort to curate research PBF-LM data at scale for PBF-LM. The potential impact of such a database is to promote federated data for PBF-LM researchers, which allows for data-driven model development to have increased usability
A geometry-based comprehensive heat source model for FE thermal simulation of laser directed energy deposition
No full textLaser Directed Energy Deposition (L-DED) is a distinctive manufacturing process known for its relatively high deposition rate, minimal waste, and ability to make complex geometries. Accurate prediction of the temperature distribution and thermal history during L-DED is crucial for estimating the microstructure, porosity, and mechanical properties of the fabricated parts. However, existing analytical and numerical models often fall short in accuracy due to overlooking the geometrical characteristics and shape of the deposition. To address this issue, a multi-step statistical/numerical analysis workflow is proposed to elucidate the thermal responses in L-DED deposited tracks. First, a data-driven predictive model using statistical methods was used to estimate the deposition geometry based on the key process parameters which are laser power (P), powder feed rate (F), and scanning speed (V). Next, the prediction results were implemented in a dynamic hybrid quiet/inactive elemental control scheme to capture the deposition process. Further, activated elements are subsequently analyzed thermally through a transient 3-D finite element (FE) heat source model accounting for heat flux from conduction, convection, and radiation. The laser beam’s energy follows a two-dimensional Gaussian distribution, while the heat flux over the actual deposition region, modeled as a quarter-ellipsoid with the predicted geometrical characteristics. This representation captures the actual projection of the laser beam on the deposition. The simulated melt pool depths and temperature showed excellent agreement with experimental measurements for L-DED depositions of Inconel 625 superalloy, exhibiting less than 10% deviation, thereby validating the proposed heat source model
The Legend of Pheidippides
No full textThe Athenian hills were merciless, their jagged, sun-scorched stones biting into the tattered remnants of Pheidippides’ leather sandals with each strained step. His feet, raw and blistered from days of relentless running, throbbed with a pain so deep he feared it had pierced into his very bones. The frayed, dust-stained straps of his sandals had long ceased to offer any real protection. Each stride sent shocks through his swollen muscles, yet Pheidippides felt as though he were gliding, his mind numb to the agony that threatened to consume him. Only his purpose remained, clear and urgent, bound to him as tightly as the hastily written message strapped to his belt.
The memory of the past week’s events flashed before his eyes, triggered by each dull thud of his feet against the earth and a desire to quicken time’s passing. Just a day earlier, he had been chosen as the hemerodromos —the swift-footed messenger—entrusted with delivering a plea to the Spartan ephors for aid, leaving what felt like the entirety of Athens\u27 fate resting on his shoulders
Shadows of Conquest
No full textDaylight spilled through the open folds of Alexander’s tent, casting a warm glow on the finely woven rugs that softened the ground beneath their boots. The air was thick with the scent of figs and sun-warmed leather, mingling with the faint aroma of oil from the gilded armour resting on a polished wooden stand near the back. Embroidered tapestries hung along the walls, bearing the symbols of Macedon and Persia—the sun and the lion intertwined—a visual declaration of Alexander’s expanding empire. A bronze basin glimmered in the corner, reflecting the light, while untouched goblets sat abandoned among a scattering of scrolls and maps on the low table. Hephaestion stood dutifully at Alexander’s right, as he often did, hands clasped behind his back. His eyes rested on the king, who leaned forward over the table, a finger tracing the eastern edge of the map with a wistful precision. There was a fire in Alexander’s gaze—a gleam Hephaestion knew well. It was the spark that could rally armies or raze cities, a force that inspired both awe and fear
Contributions of aquatic environments to household health expenditure: Empirical evidence from Japan
No full textA growing number of academic works have presented empirical evidence on the positive impacts of nature exposure on human health, however, the associations between surrounding nature (especially aquatic environments) and health expenditure have been rarely examined up until now. The major purpose of this paper is to fill in this research gap using health expenditure data at the household level and fine-scale land cover information that was reclassified into four categories (i.e. deciduous forests, evergreen forests, inland freshwater and coastal saltwater). Employing a classical health economics approach, namely, a two-part model with a generalized linear model, this study found that freshwater coverage around residence would have significantly inverse effects on household health spending. As no such significant associations were found for other land cover types, this highlights the importance of surrounding freshwater environments in determining household health expenditure. These findings were mostly robust to the alternative model specifications and different buffer sizes around residence
An Empirical Study on Restrictive Laws and Regulations Affecting Women’s Economic Participation
No full textThe global emphasis on women\u27s economic participation has grown significantly due to its vital role in promoting macroeconomic stability and advancing financial inclusion. Involving women in economic activities is essential for achieving Sustainable Development Goals, such as poverty alleviation and closing gender gaps. However, a range of regulatory, cultural, and structural barriers continue to hinder women’s ability to participate in the mainstream economy. This study aims to examine the impact of restrictive laws and regulations on women’s economic participation within the BRICS bloc. Women’s economic participation has been examined through three key dimensions: paid employment, political representation, and entrepreneurship. The findings suggest that the removal of restrictive laws and regulations is associated with increased levels of women\u27s economic participation. It is important to acknowledge that while BRICS countries have made significant strides in dismantling legal barriers affecting women, substantial obstacles remain from both legal and regulatory perspectives that hinder women’s engagement in economic activities. Therefore, the study recommends that BRICS nations prioritize the complete removal of restrictive laws and regulations impacting various aspects of women\u27s lives, including mobility, pay, marriage, and entrepreneurship.. Furthermore, ensuring a gender-equitable distribution of resources should be a central focus in policymaking to ensure that no one is left behind in the development agenda, particularly women and children
Mac Mapping in the Map Library by Colleen Beard
No full textwrites through passage revisits Colleen Beard\u27s Mac Mapping in the Map Library, which was originally published in the ACMLA Bulletin Number 76, 1990
An Outpost of Digital Hope: Frank Odasz and the Lost Promise of Grassroot Networking
No full textThis interview with Frank Odasz, a pioneering educator and technologist, chronicles the arc of rural community networking from its earliest days through the internet’s rapid commercialization. Born in rural Wyoming and educated in California during the rise of Silicon Valley, Odasz’s journey embodies the tensions and possibilities at the heart of alternative technology movements. His creation of the Big Sky Telegraph—a network for rural teachers and communities in Montana—became a touchstone for grassroots, people-centered computing long before the World Wide Web, drawing inspiration from the culture of early electronic bulletin board systems and colorful figures like David Hughes. Odasz’s candid reflections illuminate how rural challenges—lack of infrastructure, skepticism toward digital technologies, and the need for self-sufficiency—fostered innovation, collaboration, and a vision for networked empowerment outside urban and corporate centers.
The conversation traces the successes and limitations of early community networks, the profound impact of technological shifts such as the advent of the web browser, and the complex consequences of the internet’s commercialization and privatization. Odasz articulates both the promise and the losses: as the web grew, collaborative grassroots networks faded, supplanted by corporate platforms and new barriers to digital self-determination. His experiences teaching digital literacy in Indigenous and remote Alaskan communities, and his ongoing advocacy for inclusive, empowering uses of technology, challenge the field to reckon with both historical lessons and urgent contemporary risks—from misinformation to deepfakes and the social costs of digital divide. The interview offers essential insights into the history of computing, alternative technology, and the unfinished project of building equitable, community-driven digital futures
Neuroscience and Market Dynamics: The Impact of Smoking Withdrawal Syndrome on the Stock Performance of Tobacco Companies
No full textThis study investigates the effect of the annual \u27No-Smoking Day\u27 on the stock performance of British American Tobacco (BATS) and Imperial Brands (IMB) from 1997 to 2023. Our findings reveal a significant negative impact of No-Smoking Wednesdays on BATS, with a moderate but statistically significant effect on IMB. To enhance robustness, we also perform a panel data analysis, which underscores the consistent negative effect of No-Smoking Day on the tobacco sector as a whole. These results suggest that No-Smoking Day generates a calendar-based effect on stock prices, challenging the Efficient Market Hypothesis. Beyond the behavioral effects tied to the anti-smoking campaign, this study introduces a novel perspective by linking investor behavior with neurological factors, particularly Nicotine Withdrawal Syndrome (NWS). NWS, characterized by irritability, anxiety, and mood disturbances, may influence investor sentiment, even among smokers who do not intend to quit. These withdrawal symptoms could induce stress and emotional responses, thereby affecting investor behavior and contributing to negative returns. Our findings align with prior behavioral studies and highlight the role of both psychological and neurobiological factors in shaping market dynamics. Future research should examine the combined effects of anti-smoking campaigns and NWS on investor behavior and market outcomes. Additionally, the varying statistical significance across firms suggests that the diversification of tobacco companies into non-traditional products warrants further investigation