Case study of the additive manufacturing application in the supersonic flow researches

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jefte da Silva Guimarães ◽  
Valéria Serrano Faillace Oliveira Leite ◽  
Marco Antonio Sala Minucci ◽  
Dermeval Carinhana
Keyword(s):  
Additive Manufacturing ◽  
Supersonic Flow ◽  
3D Printing ◽  
Dimensional Change ◽  
Supersonic Combustion ◽  
Measuring System ◽  
Content Type ◽  
Before And After ◽  
New Perspective

Purpose The purpose of this paper is to demonstrate the aerodynamic behavior of a supersonic combustion test bench (SCTB) components, as the transition piece and the combustor of a scramjet (supersonic combustion ramjet), manufactured by 3D printing or additive manufacturing (AM). Design/methodology/approach For the dimensional and structural analysis of the manufactured models, a portable 3D scanner was used to generate the mesh of its dimensions, and to compare them before and after the experiments, a roughness measuring system was also used to verify the roughness inside the models before and after the tests, as roughness is an important parameter because it directly affects the boundary layer. For the visualization of the flow, the non-intrusive schlieren optical technique was used. Findings The experiments were carried out on the SCBT for Mach 2 flows, using the manufactured prototypes and showed that there was no structural and dimensional change of the model after the test batteries. It was found that the roughness presented by the material did not affect the quality of the flow generated. This shows that the investigated material can also be applied in experiments with supersonic flow. Originality/value This paper presents that it is possible to use in ground test facilities, for the studies of supersonic flow (in cold condition), pieces and models manufactured by 3D printing without affecting the quality of the flow generated during the experiments. This study presents a new perspective to approach AM applied in the studies of supersonic flows.

Hybrid Metal 3D Printing for Selective Polished Surface

2021 ◽  
Vol 1027 ◽  
pp. 136-140
Author(s):  
Sze Yi Mak ◽  
Kwong Leong Tam ◽  
Ching Hang Bob Yung ◽  
Wing Fung Edmond Yau
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Surface Finishing ◽  
Polished Surface ◽  
Post Processing ◽  
One Stop ◽  
Metal 3D Printing ◽  
Critical Challenge ◽  
Metal Additive

Metal additive manufacturing has found broad applications in diverse disciplines. Post processing to homogenize and improve surface finishing remains a critical challenge to additive manufacturing. We propose a novel one-stop solution of adopting hybrid metal 3D printing to streamlining the additive manufacturing workflow as well as to improve surface roughness quality of selective interior surface of the printed parts. This work has great potential in medical and aerospace industries where complicated and high-precision additive manufacturing is anticipated.

Design and optimization of projection stereolithography additive manufacturing system with multi-pass scanning

2021 ◽  
Vol 27 (3) ◽  
pp. 636-642
Author(s):  
Qin Qin ◽  
Jigang Huang ◽  
Jin Yao ◽  
Wenxiang Gao
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing System ◽  
Content Type ◽  
Design And Optimization ◽  
Compensation Algorithm ◽  
The Poor ◽  
Building Area ◽  
Projection Stereolithography ◽  
Stitching Errors

Purpose Scanning projection-based stereolithography (SPSL) is a powerful technology for additive manufacturing with high resolution as well as large building area. However, the surface quality of stitching boundary in an SPSL system has been rarely studied, and no positive settlement was proposed to address the poor stitching quality. This paper aims to propose an approach of multi-pass scanning and a compensation algorithm for multi-pass scanning process to address the issue of poor stitching quality in SPSL systems. Design/methodology/approach The process of multi-pass scanning is realized by scanning regions repeatedly, and the regions can be cured simultaneously because of the very short repeat exposure time and very fast scanning. Then, the poor stitching quality caused by the non-simultaneous curing can be eliminated. Also, a compensation algorithm is designed for multi-pass scanning to reduce the stitching errors. The validity of multi-pass scanning is verified by curing depth test, while the performance of multi-pass scanning as well as proposed compensation algorithm is demonstrated by comparing with that of a previous SPSL system. Findings The results lead to a conclusion that multi-pass scanning with its compensation algorithm is an effective approach to improve the stitching quality of an SPSL system. Practical implications This study can provide advice for researchers to achieve the satisfactory surface finish with SPSL technology. Originality/value The authors proposed a process of multi-pass scanning as well as a compensation algorithm for SPSL additive manufacturing (system to improve the stitching quality, which has rarely been studied in previous work.

scholarly journals A Parasite Biomarker Set for Evaluating Benznidazole Treatment Efficacy in Patients with Chronic Asymptomatic Trypanosoma cruzi Infection

2019 ◽  
Vol 63 (10) ◽  
Author(s):  
Adriana Egui ◽  
M. Carmen Thomas ◽  
Ana Fernández-Villegas ◽  
Elena Pérez-Antón ◽  
Inmaculada Gómez ◽  
...  
Keyword(s):  
T Cells ◽  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Parasite Load ◽  
Drastic Reduction ◽  
Content Type ◽  
Short Period ◽  
Before And After ◽  
Cruzi Infection

ABSTRACT One of the current greatest challenges of Chagas disease is the establishment of biomarkers to assess the efficacy of drugs in a short period of time. In this context, the reactivity of sera from 66 adults with chronic indeterminate Chagas disease (IND) for a set of four Trypanosoma cruzi antigens (KMP11, PFR2, HSP70, and 3973d) was analyzed before and after benznidazole treatment. The results showed that the reactivity against these antigens decreased at 9, 24, and 48 months after treatment. Moreover, the 42.4% and 68.75% of IND patients met the established standard criteria of therapeutic efficacy (STEC) at 24 and 48 months posttreatment, respectively. Meeting the STEC implied that there was a continuous decrease in the reactivity of the patient sera against the four antigens after treatment and that there was a substantial decrease in the reactivity for at least two of the antigens. This important decrease in reactivity may be associated with a drastic reduction in the parasite load, but it is not necessarily associated with a parasitological cure. After treatment, a positive PCR result was only obtained in patients who did not meet the STEC. The percentage of granzyme B+/perforin+ CD8+ T cells was significantly higher in patients who met the STEC than in those who did not meet the STEC (35.2% versus 2.2%; P < 0.05). Furthermore, the patients who met the STEC exhibited an increased quality of the multifunctional response of the antigen-specific CD8+ T cells compared with that in the patients who did not meet the STEC.

Assessment of food heritage to improve virtuous cycles

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fahimeh Khatami ◽  
Enrico Sorano ◽  
Marco Bechis
Keyword(s):  
Local Food ◽  
Methodological Approach ◽  
Western Country ◽  
Tourism Industry ◽  
Local Foods ◽  
Food Services ◽  
Traditional Foods ◽  
Content Type ◽  
New Perspective

PurposeThe purpose of this paper is to contribute the advancement of knowledge on food heritage and indigenous entrepreneurship in a non-Western country, specifically in the Persian gardens as the touristic destination for increasing the tourism and food businesses in Iran.Design/methodology/approachThe methodological approach adopted is based on qualitative and quantitative approaches to compare two representative gardens named as Bagh-Chehel-Sotoun and Bagh-Fin, as famous examples of a Persian garden in Iran. The methods supported the research to explain the lack of strategies for improving virtuous cycles in Persian gardens despite their potentials as the main places to attract many tourists.FindingsRegarding local food and the quality of servicing, most of the visitors and tourists (85–90%) had interest to test local and traditional foods around both gardens, but they had no sufficient awareness of Iranian traditional foods. According to the tourists’ interests, the authors concluded the lack of servicing and facilities to present and introduce local and traditional food for tourists.Research limitations/implicationsDespite the limitation of local food services and lack of awareness of tourists about local foods, the implication of the study offers possible avenues to promote local food business.Practical implicationsThe results could be useful for cultural heritage and tourism organizations and for investors in the economic sector due to more exploitation of the tourism industry.Originality/valueThe paper is the first work evaluating the Persian garden with a new perspective of local foods in Iran.

scholarly journals Quality of work, economic crisis, and temporary employment

2019 ◽  
Vol 41 (1) ◽  
pp. 37-51 ◽  
Author(s):  
Xavier Bartoll ◽  
Raul Ramos
Keyword(s):  
Economic Crisis ◽  
Temporary Employment ◽  
Structural Equations ◽  
Work Quality ◽  
Content Type ◽  
Crisis Period ◽  
Quality Of Work ◽  
Before And After ◽  
Different Dimensions

Purpose The purpose of this paper is to analyse the association between the type of contract (temporary vs permanent) and the quality of work and its different dimensions before and after the economic crisis among Spanish employees. Design/methodology/approach Structural equations techniques are used to analyse the association between the type of contract and the work quality and its different dimensions before and after the crisis. Data are drawn from the 2006/2007 and 2009/2010 waves of the Encuesta de Calidad de Vida en el Trabajo. Findings The results show that in the two considered periods there are no differences in quality of work among male involuntary temporary workers and those with permanent contracts. However, there is an adverse widening gap across all dimensions of work quality for women in involuntary temporary employment during the economic crisis. There is also a shift among men and women in involuntary temporary employment from valuing intrinsic job quality dimension in the pre-crisis period to valuing more the work environment dimension during the crisis period. Research limitations/implications The analysis is limited by the continuity of variables across years and the high proportion of missing values in some variables. The obtained results cannot be interpreted in terms of causality. Originality/value This is the first study to consider whether the deterioration in the Spanish labour market during the crisis has affected the relationship between the type of contract and the different dimensions of the quality of work.

scholarly journals Emotions in leaders’ enactment of professional agency

2019 ◽  
Vol 31 (2) ◽  
pp. 143-165 ◽  
Author(s):  
Päivi Hökkä ◽  
Katja Vähäsantanen ◽  
Susanna Paloniemi ◽  
Sanna Herranen ◽  
Anneli Eteläpelto
Keyword(s):  
Qualitative Content Analysis ◽  
Leadership Coaching ◽  
Content Type ◽  
Current State ◽  
Before And After ◽  
State Of Affairs ◽  
Practical Implications ◽  
A Current

Purpose Although there has been an increase in workplace studies on professional agency, few of these have examined the role of emotions in the enactment of agency at work. To date, professional agency has been mainly conceptualised as a goal-oriented, rational activity aimed at influencing a current state of affairs. Challenged by this, this study aims to elaborate the nature and quality of emotions and how they might be connected to the enactment of professional agency. Design/methodology/approach Data are collected in the context of a leadership coaching programme that aimed to promote the leaders’ professional agency over the course of a year. The participants (11 middle-management leaders working in university and hospital contexts) were interviewed before and after the programme, and the data were analysed using qualitative content analysis. Findings Findings showed that emotions played an important role in the leaders’ enactment of professional agency, as it pertained to their work and to their professional identity. The study suggests that enacting professional agency is by no means a matter of purely rational actions. Practical implications The study suggests that emotional agency can be learned and enhanced through group-based interventions reflecting on and processing one’s own professional roles and work. Originality/value As a theoretical conclusion, the study argues that professional agency should be reconceptualised in such a way as to acknowledge the importance of emotions (one’s own and those of one’s fellow workers) in practising agency within organisational contexts.

On the verge of disruption: rethinking position and role – the case of additive manufacturing

2019 ◽  
Vol 34 (5) ◽  
pp. 1093-1105 ◽  
Author(s):  
Christina Öberg ◽  
Tawfiq Shams
Keyword(s):  
Supply Chain ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Design Methodology ◽  
Secondary Data ◽  
Point Of View ◽  
Disruptive Technology ◽  
Content Type ◽  
Business Cases ◽  
Metal 3D Printing

Purpose With the overarching idea of disruptive technology and its effects on business, this paper focuses on how companies strategically consider meeting the challenge of a disruptive technology such as additive manufacturing. The purpose of this paper is to describe and discuss changes in positions and roles related to the implementation of a disruptive technology. Design/methodology/approach Additive manufacturing could be expected to have different consequences for parties based on their current supply chain positions. The paper therefore investigates companies’ strategies related to various supply chain positions and does so by departing from a position and role point of view. Three business cases related to metal 3D printing - illustrating sub-suppliers, manufacturers and logistics firms - describe as many strategies. Data for the cases were collected through meetings, interviews, seminars and secondary data focusing on both current business activities related to additive manufacturing and scenarios for the future. Findings The companies attempted to defend their current positions, leading to new roles for them. This disconnects the change of roles from that of positions. The changed roles indicate that all parties, regardless of supply chain positions, would move into competing producing roles, thereby indicating how a disruptive technology may disrupt network structures based on companies’ attempts to defend their positions. Originality/value The paper contributes to previous research by reporting a disconnect between positions and roles among firms when disruption takes place. The paper further denotes how the investigated firms largely disregarded network consequences at the disruptive stage, caused by the introduction of additive manufacturing. The paper also contributes to research on additive manufacturing by including a business dimension and linking this to positions and roles.

Customized design and additive manufacturing of kids’ ankle foot orthosis

2020 ◽  
Vol 26 (10) ◽  
pp. 1677-1685 ◽  
Author(s):  
Harish Kumar Banga ◽  
Parveen Kalra ◽  
Rajendra M. Belokar ◽  
Rajesh Kumar
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Gait Cycle ◽  
Foot Drop ◽  
Human Gait ◽  
Content Type ◽  
Ankle Foot Orthosis ◽  
New Material ◽  
Foot Orthosis

Purpose The purpose of this study is improvement of human gait by customized design of ankle foot orthosis (AFO). An has been the most frequently used orthosis in children with cerebral palsy. AFOs are designed to boost existing features or to avoid depression or traumatize muscle contractures. The advantages of AFO’s utilized for advancement in human walk attributes for the improvement in foot deformities patients or youngsters with spastic loss of motion. In this research on the customized design of AFO's to improve gait, there are limitations during walking of foot drop patients. In children with foot drops, specific AFOs were explicitly altered to improve parity and strength which are beneficial to walking positions. Design/methodology/approach This study proposes the customized design of AFOs using computerized and additive manufacturing for producing advances to alter the design and increase comfort for foot drop patients. Structuring the proposed design fabricated by using additive manufacturing and restricted material, the investigation was finalized at the Design Analysis Software (ANSYS). The system that performs best under investigation can additionally be printed using additive manufacturing. Findings The results show that the customized design of AFOs meets the patient’s requirements and could also be an alternative solution to the existing AFO design. The biomechanical consequences and mechanical properties of additive manufactured AFOs have been comparable to historically synthetic AFOs. While developing the novel AFO designs, the use of 3D printing has many benefits, including stiffness and weight optimization, to improve biomechanical function and comfort. To defeat the issues of foot drop patients, a customized AFO is used to improve the human gait cycle with new material and having better mechanical properties. Originality/value This research work focuses on the biomechanical impacts and mechanical properties of customized 3D-printed AFOs and compares them to traditionally made AFOs. Customized AFO design using 3D printing has numerous potential advantages, including new material with lightweight advancement, to improve biomechanical function and comfort. Normally, new applications mean an incremental collection of learning approximately the behavior of such gadgets and blending the new design, composite speculation and delivered substance production. The test results aim to overcome the new AFO structure issues and display the limited components and stress examination. The outcome of the research is the improved gait cycle of foot drop patients.

A finned-riser design to avoid the capillarity effect in multi-jet fusion technology

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mattia Mele ◽  
Giampaolo Campana ◽  
Gian Luca Monti
Keyword(s):  
Analytical Model ◽  
Dimensional Accuracy ◽  
Measuring System ◽  
Original Design ◽  
Heat Management ◽  
Convex Shape ◽  
Content Type ◽  
Riser Design ◽  
Under Construction

Purpose Multi-jet fusion (MJF) process is based on a polymeric powder bed that is heated and irradiated by infra-red lamps. The layer under construction is jetted with inks to provide the desired heat management conditions for selective melting. Depending on several process variables, manufactured parts can exhibit lifting of the borders of the top surface of the shape under construction. This phenomenon is related to the capillarity effect. As a result, the top surface of MJF-manufactured parts can present a peculiar convex shape. This study aims to propose a solution that instead induces the capillarity effect outside of the part under construction. Design/methodology/approach A specific design is developed to avoid the capillarity effect in MJF. It is based on an analytical model that was previously developed by the authors to estimate the shape and extent of the capillary on top surfaces of benchmark components. The proposed methodology is established by the predicted calculation of maximum values of capillarity rise and length, and safety factors. A fin-shaped geometry is designed to avoid the capillarity effect. An experimental campaign is implemented to verify the effectiveness of the proposed solution. Prototypes are manufactured by an HP MultiJet 4200 in the original design and the so-called finned-riser design, by adding a well-dimensioned appendage on the top surface to shift the capillarity effect outside the border of the part under construction. Measurements are done by a CAM2 ScanArm contactless measuring system to achieve the real shape of top surfaces. Geomagic Control X software by 3D systems is used to evaluate the quality of measured surfaces in comparison with the expected geometry of the top plane of the benchmark. Findings The investigated approach involves adding an auxiliary finned-shape appendage, which acts similarly to the risers in foundry technology, to the top surface of the part that is being produced by MJF technology. The procedure and rules for determining the dimensions of the fin are established based on physical considerations and process modelling. The method is then applied to a prototype part, which is designed to highlight the effectiveness of the finned-riser design for improving the dimensional accuracy of the top surfaces of products manufactured by the MJF process. Experimental measurements of top surfaces of the original benchmark are compared to the same ones in the case of the finned-riser benchmark. Reported results are satisfactory, and the capillary effect occurred in the fins outside the border edges of the part. Further developments are planned to extend the proposed design. Originality/value MJF technology is attracting large interest from manufacturers to produce mass customised products. The quality of manufactured parts could be affected by peculiar defects related to process parameters. The present work aims to show a method to avoid the capillarity effect. It is based on an original analytical model developed by the authors and implemented successfully in the case of a benchmark geometry.

Why privacy is not enough privacy in the context of “ubiquitous computing” and “big data”

2014 ◽  
Vol 12 (2) ◽  
pp. 93-106 ◽  
Author(s):  
Tobias Matzner
Keyword(s):  
Big Data ◽  
Ubiquitous Computing ◽  
New Technologies ◽  
Personal Data ◽  
Quality Of Data ◽  
Content Type ◽  
Privacy Threats ◽  
New Concepts ◽  
New Perspective

Purpose – Ubiquitous computing and “big data” have been widely recognized as requiring new concepts of privacy and new mechanisms to protect it. While improved concepts of privacy have been suggested, the paper aims to argue that people acting in full conformity to those privacy norms still can infringe the privacy of others in the context of ubiquitous computing and “big data”. Design/methodology/approach – New threats to privacy are described. Helen Nissenbaum's concept of “privacy as contextual integrity” is reviewed concerning its capability to grasp these problems. The argument is based on the assumption that the technologies work, persons are fully informed and capable of deciding according to advanced privacy considerations. Findings – Big data and ubiquitous computing enable privacy threats for persons whose data are only indirectly involved and even for persons about whom no data have been collected and processed. Those new problems are intrinsic to the functionality of these new technologies and need to be addressed on a social and political level. Furthermore, a concept of data minimization in terms of the quality of the data is proposed. Originality/value – The use of personal data as a threat to the privacy of others is established. This new perspective is used to reassess and recontextualize Helen Nissenbaum's concept of privacy. Data minimization in terms of quality of data is proposed as a new concept.

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