Search results

Honeycombs enjoy wide use in various engineering applications. The emergence of additive manufacturing (AM) as a method of customisable of parts has enabled the reinvention of the honeycomb structure. However, research on in-plane compressive performance of both classical and new types of honeycombs fabricated via AM is still ongoing. Several important findings have emerged over the past years, with significance for the AM community and a review is considered necessary and timely. This paper aims to review the in-plane compressive performance of AM honeycomb structures.

This paper provides a state-of-the-art review focussing on the in-plane compressive performance of AM honeycomb structures, covering both polymers and metals. Recently published studies, over the past six years, have been reviewed under the specific theme of in-plane compression properties.

The key factors influencing the AM honeycombs' in-plane compressive performance are identified, namely the geometrical features, such as topology shape, cell wall thickness, cell size and manufacturing parameters. Moreover, the techniques and configurations commonly used for geometry optimisation toward improving mechanical performance are discussed in detail. Current AM limitations applicable to AM honeycomb structures are identified and potential future directions are also discussed in this paper.

This work evaluates critically the primary results and findings from the published research literature associated with the in-plane compressive mechanical performance of AM honeycombs.

This study aims to investigate the behaviour of soft lattices, i.e. lattices capable of reaching large deformations, and the influence of the printing process on it. The authors focused on two cell topologies, the body-centred cubic (BCC) and the Kelvin, characterized by a bending-dominated behaviour relevant to the design of energy-absorbing applications.

The authors analysed the experimental and numerical behaviour of multiple BCC and Kelvin structures. The authors designed homogenous and graded arrays of different dimensions. The authors compared their technical feasibility with two three-dimensional-printed technologies, such as the fused filament fabrication and the selective laser sintering, choosing thermoplastic polyurethane as the base material.

The results demonstrate that multiple design aspects determine how the printing process influences the behaviour of soft lattices. Besides, a graded distribution of the material could contribute to fine-tuning this behaviour and mitigating the influence of the printing process.

Despite being less explored than their rigid counterpart, soft lattices are now becoming of great interest, especially when lightweight, wearable and customizable solutions are needed. This study contributes to filling this gap.

Only a few studies analyse design and printing issues of soft lattices due to the intrinsic complexity of printing flexible materials.

This study aims to propose and evaluate the progress in the basic-pixel (a strategy to generate continuous trajectories that fill out the entire surface) algorithm towards performance gain. The objective is also to investigate the operational efficiency and effectiveness of an enhanced version compared with conventional strategies.

For the first objective, the proposed methodology is to apply the improvements proposed in the basic-pixel strategy, test it on three demonstrative parts and statistically evaluate the performance using the distance trajectory criterion. For the second objective, the enhanced-pixel strategy is compared with conventional strategies in terms of trajectory distance, build time and the number of arcs starts and stops (operational efficiency) and targeting the nominal geometry of a part (operational effectiveness).

The results showed that the improvements proposed to the basic-pixel strategy could generate continuous trajectories with shorter distances and comparable building times (operational efficiency). Regarding operational effectiveness, the parts built by the enhanced-pixel strategy presented lower dimensional deviation than the other strategies studied. Therefore, the enhanced-pixel strategy appears to be a good candidate for building more complex printable parts and delivering operational efficiency and effectiveness.

This paper presents an evolution of the basic-pixel strategy (a space-filling strategy) with the introduction of new elements in the algorithm and proves the improvement of the strategy’s performance with this. An interesting comparison is also presented in terms of operational efficiency and effectiveness between the enhanced-pixel strategy and conventional strategies.

The purpose of this paper is to introduce an approach in measuring the shielding gas flow within laser powder bed fusion (L-PBF) machines under near-process conditions (regarding oxygen content and shielding gas flow).

The measurements are made sequentially using a hot-wire anemometer. After a short introduction into the measurement technique, the system which places the measurement probe within the machine is described. Finally, the measured shielding gas flow of a commercial L-PBF machine is presented.

An approach to measure the shielding gas flow within SLM machines has been developed and successfully tested. The use of a thermal anemometer along with an automated probe-placement system enables the space-resolved measurement of the flow speed and its turbulence.

The used single-normal (SN) hot-wire anemometer does not provide the flow vectors’ orientation. Using a probe with two or three hot-films and an improved placement system will provide more information about the flow and less disturbance to it.

A measurement system which allows the measurement of the shielding gas flow within commercial L-PBF machines is presented. This enables the correlation of the shielding gas flow with the resulting parts’ quality.

The study aims to analyse library user preferences in the willingness to read and pay for e-books, using a sample of both active readers (users of public library services) and non-users (the general population).

Two empirical surveys were conducted from August to November of 2019; the research sample consisted of 1,334 users from the Municipal Library of Prague and 1,101 non-users from the general Czech population. The research was focussed on e-book user preferences. The willingness to pay (WTP) for e-book services and the determinants that affect this willingness were also examined.

The results show the specific approach of Czech readers, whose main determinant of WTP is not the content, but the price and method of its payment (allocation). Some people prefer a cheaper annual lump sum, whereas others may prefer a charge of small regular fees. The decision to pay depends on their reading or payment habits.

This study also aims to clarify the demand for various types of digital media in Czech libraries and the preferred distribution models. Furthermore, the study determines the dependence of the preferences of library users in their WTP for e-books using different evaluation models. The originality of this study is in the evaluation of the determinants of WTP for e-books, which makes this study unique, and the findings should contribute to the expansion of existing knowledge in the field of information science.

This paper aims to assess how patient safety culture and incident reporting differs across different professional groups and between long-term and acute care. The Hospital Survey On Patient Safety Culture (HSPOSC) questionnaire was used to assess patient safety culture. Data from the organizations’ incident reporting system was also used to determine the number of reported patient safety incidents.

Patient safety culture is part of the organizational culture and is associated for example to rate of pressure ulcers, hospital-acquired infections and falls. Managers in health-care organizations have the important and challenging responsibility of promoting patient safety culture. Managers generally think that patient safety culture is better than it is.

Based on statistical analysis, acute care professionals’ views were significantly positive in 8 out of 12 composites. Managers assessed patient safety culture at a higher level than other professional groups. There were statistically significant differences (p = 0.021) in frequency of events reported between professional groups and between long-term and acute care (p = 0.050). Staff felt they did not get enough feedback about reported incidents.

The study reveals differences in safety culture between acute care and long-term care settings, and between professionals and managers. The staff felt that they did not get enough feedback about reported incidents. In the future, education should take these factors into consideration.

Benford's Law is an empirical observation about the frequency of digits in a variety of naturally occurring data sets. Auditors and forensic scientists have used Benford's Law to detect erroneous data in accounting and legal usage. One well-known limitation is that Benford's Law fails when data have clear minimum and maximum values. Many kinds of education data, including assessment scores, typically include hard maximums and therefore do not meet the parametric assumptions of Benford's Law. This paper implements a transformation procedure which allows for assessment data to be compared to Benford's Law. As a case study, a data quality assessment of oral language scores from the Early Childhood Longitudinal Study, Kindergarten (ECLS-K) study is used and higher risk data segments detected. The same method could be used to evaluate other concerns, such as test fraud, or other bounded datasets.

This chapter examines the phenomenon of internet users attempting to report and prevent online child sexual exploitation (CSE) and child sexual abuse material (CSAM) in the absence of adequate intervention by internet service providers, social media platforms, and government. The chapter discusses the history of online CSE, focusing on regulatory stances over time in which online risks to children have been cast as natural and inevitable by the hegemony of a “cyberlibertarian” ideology. We illustrate the success of this ideology, as well as its profound contradictions and ethical failures, by presenting key examples in which internet users have taken decisive action to prevent online CSE and promote the removal of CSAM. Rejecting simplistic characterizations of “vigilante justice,” we argue instead that the fact that often young internet users report feeling forced to act against online CSE and CSAM undercuts libertarian claims that internet regulation is impossible, unworkable, and unwanted. Recent shifts toward a more progressive ethos of online harm minimization are promising; however, this ethos risks offering a new legitimizing ideology for online business models that will continue to put children at risk of abuse and exploitation. In conclusion, we suggest ways forward toward an internet built in the interests of children, rather than profit.

The emergence of distributed manufacturing (DM) is examined as a new form of localised production, distinct from previous manifestations of multi-domestic and indigenous production.

Supply network (SN) configuration and infrastructural provisioning perspectives were used to examine the literature on established localised production models as well as DM. A multiple case study was then undertaken to describe and explore the DM model further. A maximum variation sampling procedure was used to select five exemplar cases.

Three main contributions emerge from this study. First, the research uniquely brings together two bodies of literature, namely SN configuration and infrastructure provisioning to explore the DM context. Second, the research applies these theoretical lenses to establish the distinctive nature of DM across seven dimensions of analysis. Third, emerging DM design rules are identified and compared with the more established models of localised production, drawing on both literature and DM case evidence.

This study provides a rich SN configuration and infrastructural provisioning view on DM leading to a set of design rules for DM adoption, thus supporting practitioners in their efforts to develop viable DM implementation plans.

The authors contribute to the intra- and inter-organisational requirements for the emerging DM context by providing new perspectives through the combined lenses of SN configuration and infrastructural provisioning approaches.

The purpose of this paper is to examine evolution of the American strategy toward terrorism in the aftermath of the events of September 11, 2001. In other words, this study revolves around a key question: How and why the American security strategy toward terrorism evolved in the aftermath of the September 11 attacks in 2001? Based on the neorealist approach in international relations, this paper attempted to answer that question: first, through defining the concept of terrorism and how the Americans perceive it; second, via pinpointing the characteristic of the American counter-terrorism strategy before September 11 attacks; and third, through examining the effects of those terrorist attacks on that strategy.

The nature of the subject of this study calls for reliance on the analytical descriptive approach to highlight the role and strategy of the USA in the fight against terrorism following the events of September 11, in addition to the use of the system analysis methodology, which can identify the inputs and outputs of the system that had an impact in formulating the US counter-terrorism strategy.

This study has come up with seven findings. The first finding was that the 9/11 attacks served as a turning point of the US counter-terrorism strategy and restructured its agenda. Confronting the communist threat had been its primary objective, until terrorism came to the fore and became its first and foremost priority. The USA vowed that terrorism is its enemy and waged the war on terror to thwart its risk as a global threat. The second finding revolves around the idea of double standards in the American foreign policy. True to its long-standing tradition of favoring its own interests, in complete disregard of the interests of any other party, the USA continued to uphold the double-standards policy.

This study adds a new study to the Arab Library in the field of counter-terrorism studies, national security strategies and American foreign policy. In addition, the researcher seeks to complete the scientific effort to study the US strategy against terrorism, with a clear impact on the development of the situation in the region. This study contributes to the study of how one of the great powers in the international system, the USA, deals with the terrorist organizations that have become widespread in the Arab region.