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Manufacturer specifications for the resolution of an additive manufacturing (AM) machine can be ten times smaller (more optimistic) than the actual size of manufacturable features. Existing methods used to establish a manufacturable design rule-set are conservative piecewise-constant approximations. This paper aims to evaluate the effectiveness of a first-order model for producing improved design rule-sets for feature manufacturability, accounting for process variation.

A framework is presented which uses an interpolation method and a statistical model to estimate the minimum size for a wide range of features from a set of iterative experiments.

For an SLS process, using this approach improves the accuracy and reliability of minimum feature size estimates for a wider variety of features than assessed by most existing test artifacts.

More research is needed to provide better interpolation models, broaden applicability and account for additional geometric and process parameters which significantly impact the results. This research focuses on manufacturability and does not address dimensional accuracy of the features produced.

An application to the design of thin channels in a prosthetic hand shows the utility of the results in a real-world scenario.

This study is among the first to investigate statistical variation of “pass/fail” features in AM process characterization, propose a means of estimating minimum feature sizes for shapes not directly tested and incorporate a more efficient iterative experimental protocol.

The purpose of this paper is to explore the improvements in speed and precision achievable using straightforward closed-loop control for the gantry motion in additive manufacturing machines. The authors designed and built an economically viable demonstration system to quantify the performance improvement.

The authors develop and evaluate a low-cost closed-loop controller for the X and Y axes of an entry-level three-dimensional (3D) printer. The system developed captures and compensates for the dynamics of the motor and the belt-driven stage and detects mechanical errors, such as skipped motor steps.

The system produces path-following precision improvements of 40 and 75 per cent for two different sample trajectories. Correcting for skipped steps increases reliability and allows for more aggressive tuning of motion parameters; time savings of up to 25 per cent are seen by doubling acceleration rate.

The system presented provides an appropriate platform for further investigation into more complex, application-specific controllers and inclusion of more details of the printer dynamics that could produce still greater improvements in speed and accuracy.

The performance, low cost (40 USD/axis) and applicability to the majority of sub-2000USD 3D printer designs make this work of practical significance.

The CNC machining industry has for many years used similar approaches, but application to 3D printers has not been explored in the literature. This paper demonstrates the value of even a simple controller applicable to almost any 3D printer, while maintaining cost-effectiveness of the solution in a competitive market.

The purpose of this paper is to review available technologies, analyse their features, propose a new approach of 3D sand mould printing based on line forming, introduce the manufacturing principle and show advantages of this approach, especially for larger parts with large Z steps in the build, such as 2 mm stepwise.

This paper introduces 3D sand mould printing, compares and analyses technological process and existing fabrication approaches among available technologies first. Then, a new approach of 3D sand mould printing is proposed to improve build speed. In addition, the proposed system will be analysed or benchmarked against existing systems.

A new approach based on line forming of sand mould printing is put forward by reviewing and analysing available technologies, to improve build speed from the aspect of basic moulding movement instead of optimization of moulding methods and process parameters. The theoretical calculation and analysis shows that build speed can be improved greatly, and it is more suitable for the manufacture of large-scale casting’s sand mould when considering dimensional accuracy and printing error, as well as uniformity of each layer.

The specific implement scheme of line forming and nozzle’s specific structure of this new approach need further study.

Much higher build speed of 3D sand mould printing with new approach brings evident implication for moulds companies and manufacturing industry, having a far-reaching influence on the development of national economy.

This paper reviews available technologies and presents a new approach of 3D sand mould printing for the first time. Analysis of the new approach shows that this new method of sand mould printing can boost build speed greatly. So, its application prospect is great.

Dr. Benjamin Spock's advice to parents has been commented on and analyzed by many authors. In this article, Raymond G. McInnis outlines some of the major themes found in the criticism of Baby and Child Care, and cites important works on the subject.

Social media has been widely adopted by politicians and political parties during elections and routine times and has been discussed before. However, research in the field has so far not addressed how a political leader's private or official social media account affects their message, language and style. The current study examined how Israeli Prime Minister Benjamin Netanyahu uses his private Facebook account, compared to his use of his official Facebook page “Prime Minister of Israel.”

In this study, the author identified the differences between these two digital entities using in-depth content analysis based on all posts (N = 1,484) published on the two pages over a 12-month period between 2018 and 2019.

The study’s findings indicate that Netanyahu regularly uses his personal page to address topics that are not represented on his official page, such as mentioning and attacking political rivals, presenting political agenda, and criticizing Israeli journalists and media organizations. Netanyahu's private Facebook account is also used to comment on personal events such as the criminal indictments he is facing and family affairs.

The findings highlight the need to investigate the different identities that politicians maintain on social media when they use personal or official accounts, sometimes on the same platform. The medium matters, yet the author also discovered that a leader's choice of account and its title are also important.

The peer review history for this article is available at: https://publons.com/publon/10.1108/OIR-01-2021-0004.

The British North American colonies were the first western economies to rely on legislature-issued paper monies as an important internal media of exchange. This system arose piecemeal. In the absence of banks and treasuries that exchanged paper monies at face value for specie monies on demand, colonial governments experimented with other ways to anchor their paper monies to real values in the economy. These mechanisms included tax-redemption, land-backed loans, sinking funds, interest-bearing notes, and legal tender laws. I assess and explain the structure and performance of these mechanisms. This was monetary experimentation on a grand scale.

Drawing on sensemaking and emotion regulation research, the purpose of this paper is to reconceptualize core contributor withdrawal (CCW) in the context of online peer-production communities (OPPCs). To explain the underlying mechanisms that make core contributors withdraw from these communities, the authors propose a process theory of contributor withdrawal called the core contributor withdrawal theory (CCWT).

To support CCWT, a typology of unmet expectations of online communities is presented, which uncovers the cognitive and emotional processing involved. To illustrate the efficacy of CCWT, a case study of the English version of Wikipedia is provided as a representative OPPC.

CCWT identifies sensemaking and emotion regulation concerning contributors’ unmet expectations as causes of CCW from OPPCs, which first lead to declined expectations, burnout and psychological withdrawal and thereby to behavioral withdrawal.

CCWT clearly identifies how and why important participation transitions, such as from core contributor to less active contributor or non-contributor, take place. By adopting process theories, CCWT provides a nuanced explanation of the cognitive and affective events that take place before core contributors withdraw from OPPCs.

CCWT highlights the challenge of online communities shifting from recruiting new contributors to preventing loss of existing contributors in the maturity stage. Additionally, by identifying the underlying cognitive and affective processes that core contributors experience in response to unexpected events, communities can develop safeguards to prevent or correct cognitions and emotions that lead to withdrawal.

CCWT provides a theoretical framework that accounts for the negative cognitions and affects that lead to core contributors’ withdrawal from online communities. It furthers the understanding of what motivates contributing to and what leads to withdrawal from OPPC.

This article explores the role of history and historical memory in the formation of early Zionist/Israeli national security doctrine. To that end, it makes three moves. First, it explores a series of public addresses made by Zalman Rubashov (Shazar) in 1942–1943. A key public intellectual in the Jewish community of preindependent Palestine (the Yishuv), Rubashov means to help his listeners make sense of, and respond collectively to, the unfolding destruction of European Jewry. Second, it draws cautious parallels between those public intellectual pronouncements and the postwar work of Friedrich Meinecke, a prominent German historian and public intellectual and a sometime teacher of Rubashov. In both cases, I suggest, history does more than make sense of a moment of political transition: It seeks to reframe the self-understandings of citizens and their collective political relations. Third, drawing on a recent memoir by Noam Chayut, a prominent Israeli antioccupation activist, I explore how those self-understandings can be lost when the historical claims upon which they are predicated lose their sense of immediacy, naturalness, or coherence.

Principals play a pivotal role in teachers’ professional growth, which impacts student outcomes. The purpose of this paper is to understand the perceptions principals have about effective elements of professional development (PD) and the role they play in facilitating the growth of teachers, and how this affects student learning.

Q methodology was utilized to investigate the subjective views of public school administrators about PD. A post sort survey was used to interpret demographic and perceptual data. The Q sorts were factor analyzed to reveal statistical correlations among the administrators. Focus group interviews representative of each emergent factor were then conducted with eight of the 34 principals who sorted the statements.

In total, 31 of the participants loaded on one of three factors. Though there were perceptional differences about which PD elements are effective, all of the principals expressed a desire to take an active role in teachers’ professional growth. These distinct viewpoints of PD included the themes of sustainability and collaboration.

School leaders are commonly named as the most important influence on teachers and their practices. PD is among the significant strategies that principals employ to impact teachers. Thus, studies that provide insights into how school leaders perceive PD are crucial to the in-service development of school teachers.

Transnationalism is a multi-faceted phenomenon which has impacted on society and challenged, inter alia, the paradigm of national affiliations. The trasnationalisation of the European field has arguably contributed to a political arena where embryonic post-national identities and new forms of belonging are being negotiated, challenged and legitimised. By investigating the discourses of members of a transnational NGO of ‘active’ citizens, this chapter seeks to understand how current European identities are discursively constructed from bottom up in the public sphere. Appropriating CDA, this chapter offers insights into how discursive strategies and linguistic devices used by the speakers and predicated on the indexicality of transnational frames, construct Europe and patterns of belonging to it. This chapter suggests different conceptual dimensions of transnationalism enacted by members in discourse which are conveniently summarised as nation-centric, Euro-centric and cosmopolitan.