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Fused deposition modelling (FDM) is increasingly being explored as a commercial fabrication method due to its ability to produce net or near-net shape parts directly from a computer-aided design model. Other benefits of technology compared to conventional manufacturing include lower cost for short runs, reduced product lead times and rapid product design. High-performance polymers such as polyetherimide, have the potential for FDM fabrication and their high-temperature capabilities provide the potential of expanding the applications of FDM parts in automotive and aerospace industries. However, their relatively high glass transition temperature (215 °C) causes challenges during manufacturing due to the requirement of high-temperature build chambers and controlled cooling rates. The purpose of this study is to investigate the mechanical properties of ULTEM 1010, an unfilled polyetherimide grade.

In this research, mechanical properties were evaluated through tensile and flexural tests. Analysis of variance was used to determine the significance of process parameters to the mechanical properties of the specimens, their main effects and interactions. The fractured surfaces were analysed by scanning electron microscopy and optical microscopy and porosity was assessed by X-ray microcomputed tomography.

A range of mean tensile and flexural strengths, 60–94 MPa and 62–151 MPa, respectively, were obtained highlighting the dependence of performance on process parameters and their interactions. The specimens were found to fracture in a brittle manner. The porosity of tensile samples was measured between 0.18% and 1.09% and that of flexural samples between 0.14% and 1.24% depending on the process parameters. The percentage porosity was found to not directly correlate with mechanical performance, rather the location of those pores in the sample.

This analysis quantifies the significance of the effect of each of the examined process parameters has on the mechanical performance of FDM-fabricated specimens. Further, it provides a better understanding of the effect process parameters and their interactions have on the mechanical properties and porosity of FDM-fabricated polyetherimide specimens. Additionally, the fracture surface of the tested specimens is qualitatively assessed.

Process parameters in Fused Filament Fabrication (FFF) can affect mechanical and surface properties of printed parts. Numerous studies have reported parametric studies of various materials using full factorial and Taguchi design of experiments (DoEs). However, a comparison between the two are not well-established in literature. The purpose of this study is to compare full factorial and Taguchi DoEs to determine the effects of FFF process parameters on mechanical and surface properties of Nylon 6/66 copolymer. In addition, perform in-depth failure mechanism analysis to understand why the process parameters affect the responses.

A full factorial DoE was used to determine the effects of FFF process parameters, such as infill density, infill pattern, layer height and raster angle on responses, such as compressive strength, impact strength, surface roughness and manufacturing time of Nylon 6/66. Micro-computed tomography was used to analyse the impact test samples before and after impact and scanning electron microscope was used to understand the failure mechanism of infill and top layers. Differential scanning calorimetry (DSC) scans of infill and top layers were then taken to determine if a variation in crystallinity existed in different regions of the build.

Analysis of variance and main effects plots reveal that infill density has the greatest effect on mechanical and surface properties while manufacturing time is most affected by layer height for the polymer used. A 20% reduction in infill increased impact strength by 19% on average, X-ray images of some of the samples before and after impact tests are presented to understand the reason behind the difference. Moreover, DSC revealed a difference in the degree of crystallinity between the infill and top layers for 80% infill density samples. In addition, Taguchi DoE is realized to be a more efficient technique to determine optimum process parameters for responses that vary linearly as it reduces experimental effort significantly while providing mostly accurate results.

To the author’s knowledge, no published paper has reported a comparison between predictive DoE method with full factorial DoE to verify their accuracy in determining the effects of FFF process parameters on properties of printed parts. Also, a theory was developed based on DSC results that as the infill is printed faster, it cools slowly compared to the top layers, and hence the infill is in a less crystalline state when compared to the top layers. This increased the ductility of the infill (of 80% infill samples) and thus improved impact absorption.

In their introductory chapter, Augello and Guidi pose a number of questions related to the institutionalization of economics in what they have called “The Liberal Age.” The questions (p. 5) may be generalized to the following two. First, what were the forces of history leading to the rise of economics in the informational environment of a particular set of Western nations, and what resulting form did its institutionalization take in those nations? Second, what were the consequences for the content of economics of its being institutionalized in this way? That is, did institutionalization itself generate a recursive force of history competing with other external forces shaping economics?

Concern about special education's future is widespread. Now there are calls for special education's abandonment or its nonexistence in any environment other than general education (i.e., for full inclusion or some form of general education only). Some advocates for reform consider special education obsolete, to be rejected in favor of newer ideas known as inclusionary education, and they advocate abandoning special education.

Now may be the time for a second revolution in thinking about what special education is and does so that it evolves into a service that more consistently realizes its promise. Special education is likely to become extinct if its devolution continues. Its collapse would hasten the abandonment of public education. Alternatively, it could evolve to become a viable part of public education, a distinct entity, a clearly identifiable and viable part of educating all children appropriately in public schools.

Among the many causes of special education's devolution, some stand out prominently: (1) confusing must and may; (2) accepting illogic and imprecision of language; (3) responding to all diversities in the same way; (4) spurning science; (5) confusing attribute and person; (6) putting the worst possible face on special education; and (7) misconstruing least restrictive environment.

Better thinking and clearer communication are required to achieve special education's revitalization. These include calling things what they are and relying on new, younger leaders. Clear and wide understanding – consensus – about what special education is and does and acceptance of the idea that we must have it as a separate and distinct part of universal public education would be revolutionary.

Considers the development of local supply chains in the Republic of Kazakhstan. The reconstruction of supply chains, torn apart by the collapse of central planning, is a very important task for national economic recovery in all the transition economies but, as Western experience shows, it could be especially germane to economic development at the local and regional level. Using the results of research carried out in Kazakhstan during late 1995 and 1996, we outline the local supply chains which are beginning to emerge and attitudes towards them. The case is made for increased local policy intervention to promote local supply chain development in Kazakhstan and, by implication, elsewhere in the transition economies.

The rise of the regulatory state during the Gilded Age was closely associated with the development of institutionalist ideas in American academia. In their analysis of the emergent regulatory environment, institutionalists like John Commons operated with a fundamentally marginalist theory of value and distribution. This engagement is a central explanation for the ultimate ascendancy of neoclassical economics, and the limitations of the regulatory environment that emerged in the Progressive Era. The eventual rise of the Chicago School and its deregulatory ambitions did constitute a rupture, but one achieved without rejecting preceding conceptions of competition and value. The substantial compatibility of the view of markets underlying both the regulatory and deregulatory periods is stressed, casting doubt about the transformative potential of the resurgent regulatory impulse in the New Gilded Age.

In their Foreword, Augullo and Guidi identify the objectives behind the design features of their long-term project. One objective is to study “the history of economics from the viewpoint of the economists’ relationships with the institutional and professional environment.” A second objective is that of comparative methodology, the “systematic and meditated comparison among national cases…so that the interpretive framework of each might be enriched by cross-fertilization.” A third objective is that “economics was rooted in institutional contexts and had itself over time become an institution—a doctrinal corpus of knowledge which permeates and frames the mind of the student body, scholars, professionals and public opinion at large” and to do so “not merely from the canonical standpoint of doctrinal or paradigmatic evolution” (AG, p. xi).

By now, it is one of the standard tropes of those who write about the professionalization of American economics that there was a methodenstreit between the marginalists and the historicists at the turn of the nineteenth century into the twentieth. As recently as last year, Nancy Cohen (2002) argued that the only problem with this picture is that we have not understood correctly that the marginalists had actually won much sooner than we realized, sometime before 1900. Dorothy Ross’s classic The Origins of Amercian Social Science (1991) plays off the same dichotomy, but offers the older chronology, that “[b]etween about 1890 and 1910 marginal economics became the dominant paradigm in American economics.”

The authors speculate only about relatively short-term advances in special education for students with emotional and behavioral disorders. Speculation is confined to the overlapping areas of core values, technologies, neuroscience, and law/policy. In core values, the authors hope to see a resurgence of commitment to special, effective instruction and to practice aligned with scientific evidence. It is hoped that technologies will advance practices in instruction, improve the uses of artificial intelligence in teacher training and teaching, and encourage the appropriate use of artificial reproduction to avoid disorders. Neuroscience, it is hoped, will yield more reliable and helpful classification of disorders, better and more useful imaging, and more effective treatment of a variety of emotional, behavioral, and academic problems. In law and policy, the authors hope the Supreme Court's Endrew case will result in greater focus on challenging, appropriate education. Law and policy should also encourage trauma sensitivity in education, make whole-school approaches to trauma sensitivity the priority, and avoid universal trauma screening. Students' and families' legitimate interests in confidentiality and data privacy should be protected in newly constructed information-sharing infrastructures.