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1 – 10 of 79
Open Access
Article
Publication date: 14 March 2024

Chongjun Wu, Yutian Chen, Xinyi Wei, Junhao Xu and Dongliu Li

This paper is devoted to prepare micro-cone structure with variable cross-section size by Stereo Lithography Appearance (SLA)-based 3D additive manufacturing technology. It is…

Abstract

Purpose

This paper is devoted to prepare micro-cone structure with variable cross-section size by Stereo Lithography Appearance (SLA)-based 3D additive manufacturing technology. It is mainly focused on analyzing the forming mechanism of equipment and factors affecting the forming quality and accuracy, investigating the influence of forming process parameters on the printing quality and optimization of the printing quality. This study is expected to provide a µ-SLA surface preparation technology and process parameters selection with low cost, high precision and short preparation period for microstructure forming.

Design/methodology/approach

The µ-SLA process is optimized based on the variable cross-section micro-cone structure printing. Multi-index analysis method was used to analyze the influence of process parameters. The process parameter influencing order is determined and validated with flawless micro array structure.

Findings

After the optimization analysis of the top diameter size, the bottom diameter size and the overall height, the influence order of the printing process parameters on the quality of the micro-cone forming is: exposure time (B), print layer thickness (A) and number of vibrations (C). The optimal scheme is A1B3C1, that is, the layer thickness of 5 µm, the exposure time of 3000 ms and the vibration of 64x. At this time, the cone structure with the bottom diameter of 50 µm and the cone angle of 5° could obtain a better surface structure.

Originality/value

This study is expected to provide a µ-SLA surface preparation technology and process parameters selection with low cost, high precision and short preparation period for microstructure forming.

Details

Journal of Intelligent Manufacturing and Special Equipment, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2633-6596

Keywords

Open Access
Article
Publication date: 27 August 2020

Dieter Koemle and Xiaohua Yu

This paper reviews the current literature on theoretical and methodological issues in discrete choice experiments, which have been widely used in non-market value analysis, such…

8998

Abstract

Purpose

This paper reviews the current literature on theoretical and methodological issues in discrete choice experiments, which have been widely used in non-market value analysis, such as elicitation of residents' attitudes toward recreation or biodiversity conservation of forests.

Design/methodology/approach

We review the literature, and attribute the possible biases in choice experiments to theoretical and empirical aspects. Particularly, we introduce regret minimization as an alternative to random utility theory and sheds light on incentive compatibility, status quo, attributes non-attendance, cognitive load, experimental design, survey methods, estimation strategies and other issues.

Findings

The practitioners should pay attention to many issues when carrying out choice experiments in order to avoid possible biases. Many alternatives in theoretical foundations, experimental designs, estimation strategies and even explanations should be taken into account in practice in order to obtain robust results.

Originality/value

The paper summarizes the recent developments in methodological and empirical issues of choice experiments and points out the pitfalls and future directions both theoretically and empirically.

Details

Forestry Economics Review, vol. 2 no. 1
Type: Research Article
ISSN: 2631-3030

Keywords

Open Access
Article
Publication date: 7 August 2017

Chunlin Zhou, Huifeng Wu, Xiang Xu, Yong Liu, Qi Zhu and Shuwen Pan

The purpose of this paper is to propose a robotic system for percutaneous surgery. The key component in the system, a robotic arm that can manipulate a puncture needle is…

3938

Abstract

Purpose

The purpose of this paper is to propose a robotic system for percutaneous surgery. The key component in the system, a robotic arm that can manipulate a puncture needle is presented. The mechanical design, the motion control and the force control method of the robotic arm are discussed in the paper.

Design/methodology/approach

The arm with an arc mechanism placed on a 3D Cartesian stage is developed as a puncture needle manipulator to locate the position of the needle tip, tune the needle’s posture and actuate the puncture motion under the visual guidance of two orthogonal X-ray images of a patient by a surgeon. A focusing method by using two laser spots is proposed to automatically move the needle tip to a surgery entry point on the skin. A dynamics model is developed to control the position of the needle mechanism and an explicit force control strategy is utilized to perform the needle insertion.

Findings

With the surgical system, a surgeon can easily perform puncture operation by taking two orthogonal real-time X-ray images as a visual feedback and accurately navigating the needle insertion. The laser-guided focusing method is efficient in placement of the needle tip. The explicit force control strategy is proved to be effective for holding constant and stable puncture force in experiments.

Originality/value

The robotic arm has an advantage in easy redirection of the needle because the rotation and the translation are decoupled in the mechanism. By adopting simple laser pens and a well-developed kinematics model, the system can handle the entry point, locating task automatically. The focusing method and the force control method proposed in the paper are useful for the present system and could be intuitive for similar surgical robots.

Details

Assembly Automation, vol. 37 no. 3
Type: Research Article
ISSN: 0144-5154

Keywords

Open Access
Article
Publication date: 8 March 2022

Agostino Cortesi, Carlotta Berionni, Carina Veeckman, Chiara Leonardi, Gianluca Schiavo, Massimo Zancanaro, Marzia Cescon, Maria Sangiuliano, Dimitris Tampakis and Manolis Falelakis

The European H2020 Families_Share project aims at offering a grass-root approach and a co-designed platform supporting families for sharing time and tasks related to childcare…

1488

Abstract

Purpose

The European H2020 Families_Share project aims at offering a grass-root approach and a co-designed platform supporting families for sharing time and tasks related to childcare, parenting, after-school and leisure activities and other household tasks. To achieve this objective, the Families_Share project has been built on current practices which are already leveraging on mutual help and support among families, such as Time Banks, Social Streets and self-organizing networks of parents active at the neighbourhood level and seek to harness the potential of ICT networks and mobile technologies to increase the effectiveness of participatory innovation. The aim of this paper is to present and discuss the Families_Share methodology and platform, as well as the results obtained by several partecipating communities in different European countries.

Design/methodology/approach

This paper discusses how the Families Share approach (CAPS project, Horizon 2020) is bringing the sharing economy to childcare. Families Share developed a co-caring approach and a co-designed digital welfare platform to support parents with sharing time and tasks related to childcare, after-school and leisure activities. Families Share conducted two iterative pilot experiments and related socio-economic evaluations in six European cities. More than 3,000 citizens were engaged in the co-design process through their local community organizations and more than 1,700 parents and children actively experimented with the approach by organizing collaborative childcare activities. The authors discuss the challenges and solutions of co-designing a socio-technical approach aimed at facilitating socially innovative childcare models, and how the Families Share approach, based on technology-supported co-production of childcare, may provide a new sustainable welfare model for municipalities and companies with respect to life––work balance.

Findings

The authors discuss the challenges and solutions of co-designing a technological tool aimed at facilitating socially innovative childcare models, and how the Families Share approach may provide a new sustainable welfare model for municipalities and companies with respect to work–life balance.

Originality/value

As a main difference with state-of-the-art proposals, Families_Share is aimed to provide support to networks of parents in the organization of self-managed activities, this way being orthogonal with respect either to social-network functionalities or to supply and demand services. Furthermore, Families_Share has been based on a participative approach for both the ICT platform and the overall structure.

Details

Digital Policy, Regulation and Governance, vol. 24 no. 2
Type: Research Article
ISSN: 2398-5038

Keywords

Open Access
Article
Publication date: 3 October 2019

Lin Qi, Wenbo Zhang, Ronglai Sun and Fang Liu

Giant orthogonal grid barrel vault is generated by deleting members in the inessential force transfer path of the two-layer lattice barrel vault. Consisting of members in the…

1372

Abstract

Purpose

Giant orthogonal grid barrel vault is generated by deleting members in the inessential force transfer path of the two-layer lattice barrel vault. Consisting of members in the essential transfer path only, giant orthogonal grid barrel vault is a new type of structure with clear mechanical behavior and efficient material utilization. The paper aims to discuss this issue.

Design/methodology/approach

The geometrical configuration of this structure is analyzed, and the geometrical modeling method is proposed. When necessary parameters are determined, such as the structural span, length, vault rise, longitudinal and lateral giant grid number and section height to top chord length ratio of the lattice member, the structure geometrical model can be generated.

Findings

Numerical models of giant orthogonal grid barrel vaults with different rise–span ratios are built using the member model that can simulate the pre-buckling and post-buckling behavior. So the possible member buckle-straighten process and the plastic hinge form–disappear process of the structure under strong earthquake can be simulated.

Originality/value

Seismic analysis results indicate that when the structure damages under strong earthquake there are a large number of buckling members and few endpoint plastic hinges in the structure. Dynamic damage of giant orthogonal grid barrel vault under strong earthquake is caused by buckling members that weaken the structural bearing capacity.

Details

International Journal of Structural Integrity, vol. 11 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Open Access
Article
Publication date: 23 January 2023

Md.Tanvir Ahmed, Hridi Juberi, A.B.M. Mainul Bari, Muhommad Azizur Rahman, Aquib Rahman, Md. Ashfaqur Arefin, Ilias Vlachos and Niaz Quader

This study aims to investigate the effect of vibration on ceramic tools under dry cutting conditions and find the optimum cutting condition for the hardened steel machining…

Abstract

Purpose

This study aims to investigate the effect of vibration on ceramic tools under dry cutting conditions and find the optimum cutting condition for the hardened steel machining process in a computer numerical control (CNC) lathe machine.

Design/methodology/approach

In this research, an integrated fuzzy TOPSIS-based Taguchi L9 optimization model has been applied for the multi-objective optimization (MOO) of the hard-turning responses. Additionally, the effect of vibration on the ceramic tool wear was investigated using Analysis of Variance (ANOVA) and Fast Fourier Transform (FFT).

Findings

The optimum cutting conditions for the multi-objective responses were obtained at 98 m/min cutting speed, 0.1 mm/rev feed rate and 0.2 mm depth of cut. According to the ANOVA of the input cutting parameters with respect to response variables, feed rate has the most significant impact (53.79%) on the control of response variables. From the vibration analysis, the feed rate, with a contribution of 34.74%, was shown to be the most significant process parameter influencing excessive vibration and consequent tool wear.

Research limitations/implications

The MOO of response parameters at the optimum cutting parameter settings can significantly improve productivity in the dry turning of hardened steel and control over the input process parameters during machining.

Originality/value

Most studies on optimizing responses in dry hard-turning performed in CNC lathe machines are based on single-objective optimization. Additionally, the effect of vibration on the ceramic tool during MOO of hard-turning has not been studied yet.

Details

International Journal of Industrial Engineering and Operations Management, vol. 5 no. 1
Type: Research Article
ISSN: 2690-6090

Keywords

Open Access
Article
Publication date: 26 April 2022

Jingfeng Xie, Jun Huang, Lei Song, Jingcheng Fu and Xiaoqiang Lu

The typical approach of modeling the aerodynamics of an aircraft is to develop a complete database through testing or computational fluid dynamics (CFD). The database will be huge…

2008

Abstract

Purpose

The typical approach of modeling the aerodynamics of an aircraft is to develop a complete database through testing or computational fluid dynamics (CFD). The database will be huge if it has a reasonable resolution and requires an unacceptable CFD effort during the conceptional design. Therefore, this paper aims to reduce the computing effort required via establishing a general aerodynamic model that needs minor parameters.

Design/methodology/approach

The model structure was a preconfigured polynomial model, and the parameters were estimated with a recursive method to further reduce the calculation effort. To uniformly disperse the sample points through each step, a unique recursive sampling method based on a Voronoi diagram was presented. In addition, a multivariate orthogonal function approach was used.

Findings

A case study of a flying wing aircraft demonstrated that generating a model with acceptable precision (0.01 absolute error or 5% relative error) costs only 1/54 of the cost of creating a database. A series of six degrees of freedom flight simulations shows that the model’s prediction was accurate.

Originality/value

This method proposed a new way to simplify the model and recursive sampling. It is a low-cost way of obtaining high-fidelity models during primary design, allowing for more precise flight dynamics analysis.

Details

Aircraft Engineering and Aerospace Technology, vol. 94 no. 11
Type: Research Article
ISSN: 1748-8842

Keywords

Open Access
Article
Publication date: 25 June 2019

Anqi Xiong and Ali N. Akansu

Transaction cost becomes significant when one holds many securities in a large portfolio where capital allocations are frequently rebalanced due to variations in non-stationary…

Abstract

Purpose

Transaction cost becomes significant when one holds many securities in a large portfolio where capital allocations are frequently rebalanced due to variations in non-stationary statistical characteristics of the asset returns. The purpose of this paper is to employ a sparsing method to sparse the eigenportfolios, so that the transaction cost can be reduced and without any loss of its performance.

Design/methodology/approach

In this paper, the authors have designed pdf-optimized mid-tread Lloyd-Max quantizers based on the distribution of each eigenportfolio, and then employed them to sparse the eigenportfolios, so those small size orders may usually be ignored (sparsed), as the result, the trading costs have been reduced.

Findings

The authors find that the sparsing technique addressed in this paper is methodic, easy to implement for large size portfolios and it offers significant reduction in transaction cost without any loss of performance.

Originality/value

In this paper, the authors investigated the performance the sparsed eigenportfolios of stock returns in S&P500 Index. It is shown that the sparsing method is simple to implement and it provides high levels of sparsity without causing PNL loss. Therefore, transaction cost of managing a large size portfolio is reduced by employing such an efficient sparsity method.

Open Access
Article
Publication date: 11 January 2021

Henry Gyarteng-Mensah, De-Graft Owusu-Manu, David Edwards, Isaac Baidoo and Hatem El-Gohary

Using a discrete choice experiment (DCE), this study aims to better understand the job preference of postgraduate students studying at the Kwame Nkrumah University of Science and…

3825

Abstract

Purpose

Using a discrete choice experiment (DCE), this study aims to better understand the job preference of postgraduate students studying at the Kwame Nkrumah University of Science and Technology-Institute of Distance Learning, Ghana and also rank the attributes of a job they deem important.

Design/methodology/approach

The research adopted a positivist epistemological design contextualised within a deductive approach and case study strategy. Primary survey data was collected from a stratified random sample of 128 postgraduate students with multi-sectorial career prospects. Sample students were subjected to a DCE in which their stated preferences were collected using closed-ended questionnaires with 28 pairs of hypothetical job profiles. Respondents’ preferences from the DCE data were then modelled using the conditional logit.

Findings

The research reveals that: salary in the range GHC 2,800.00 to GHC 3,400.00 ($1 = GHS 5.3); supportive management; very challenging jobs; and jobs located in the city were the top attributes that were significant and had the most impact in increasing the utility of selecting a particular job. Interestingly, jobs with no extra hours workload were not significant hence, had a negative impact upon student preferences.

Originality/value

This novel research is the first to use a DCE to better elicit preference and trade-offs of postgraduate students in a developing country towards varying job characteristics that have an impact on their future employment decisions. Knowledge advancements made provide invaluable insight to employers and policymakers on the key criteria that should be implemented to retain the best candidate.

Details

Journal of Humanities and Applied Social Sciences, vol. 4 no. 3
Type: Research Article
ISSN:

Keywords

Open Access
Article
Publication date: 11 November 2020

Md. Hafiz Iqbal

This study provides empirical evidence of the economic valuation of ecosystem services. It examines the willingness-to-pay (WTP) and compensating surplus (CS) in response to…

1753

Abstract

Purpose

This study provides empirical evidence of the economic valuation of ecosystem services. It examines the willingness-to-pay (WTP) and compensating surplus (CS) in response to policy change based on focus group discussion (FGD) and survey.

Design/methodology/approach

A randomized conjoint analysis based experiment was conducted in seven villages of Sundarbans in Bangladesh to elicit stated preference data and measure WTP and CS. Each respondent faced three options in every choice card-two hypothetical alternatives and one status quo scheme. Four alternatives – payment for ecosystem services, storm protection, erosion control and habitat for fish breeding – are randomly and simultaneously assigned to the two alternatives.

Findings

The findings suggest that age, income, education, family size and occupational status are the influential factor to choice the relevant attributes of ecosystem services and their levels. Villagers would like to pay annually Tk. 703, Tk. 281, and Tk. 59 for lower, moderate, and higher ecosystem services. With these WTP, they get surplus Tk. 760, Tk. 138, and Tk. 346 respectively.

Research limitations/implications

The lower WTP does not necessarily imply low demand for ecosystem service, as the findings from WTP illustrate potential demand for ecosystem services of Sundarbans.

Practical implications

The study provides an important insight into the ecosystem services and values of Sundarbans mangrove forests for welfare and can inform policy for sustainable use of resources of this forest.

Originality/value

There is a crucial gap in understanding what could villagers be ready for WTP for better ecosystem services of Sundarbans mangrove forest, how do payment based ecosystem services, as a proxy for the conservation of Sundarbans mangrove, and to what extent the policy can be strengthened.

Details

Forestry Economics Review, vol. 2 no. 1
Type: Research Article
ISSN: 2631-3030

Keywords

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