The purpose is to forecasting carbon emissions from China's civil aviation more accurately, a novel fractional multivariate GM(1,N) model with interaction effects is developed in…
Abstract
Purpose
The purpose is to forecasting carbon emissions from China's civil aviation more accurately, a novel fractional multivariate GM(1,N) model with interaction effects is developed in this paper.
Design/methodology/approach
First, the interaction term, the trend terms are introduced in the grey action term to reflect the influence of the interaction between the system-related variables on the change of the system characteristic variables and the time trend of the system development. Then fractional cumulative generating sequence is used as the modeling sequence to reduce the perturbation of the original data. Finally, in order to effectively find the optimal fraction accumulation generation coefficient, the particle swarm optimization (PSO) is used to determine the emerging coefficient.
Findings
Experimental results show that FIEGM(1, N) outperforms other grey prediction models in predicting the carbon emissions of CAAC, which can better solve the problem of multivariate system prediction of small samples with trend interaction effect.
Originality/value
By considering the influence of interactions in the system and the trend of system development in combination with fractional accumulation theory, a new method to improve the prediction performance of the GM(1, N) model is proposed. The model is first applied to the prediction of carbon emission of civil aviation in China.
Details
Keywords
Three-dimensional (3D) printing technologies have gained attention in dentistry because of their ability to print objects with complex geometries with high precision and accuracy…
Abstract
Purpose
Three-dimensional (3D) printing technologies have gained attention in dentistry because of their ability to print objects with complex geometries with high precision and accuracy, as well as the benefits of saving materials and treatment time. This study aims to explain the principles of the main 3D printing technologies used for manufacturing dental prostheses and devices, with details of their manufacturing processes and characteristics. This review presents an overview of available 3D printing technologies and materials for dental prostheses and devices.
Design/methodology/approach
This review was targeted to include publications pertaining to the fabrication of dental prostheses and devices by 3D printing technologies between 2012 and 2021. A literature search was carried out using the Web of Science, PubMed, Google Scholar search engines, as well as the use of a manual search.
Findings
3D printing technologies have been used for manufacturing dental prostheses and devices using a wide range of materials, including polymers, metals and ceramics. 3D printing technologies have demonstrated promising experimental outcomes for the fabrication of dental prostheses and devices. However, further developments in the materials for fixed dental prostheses are required.
Originality/value
3D printing technologies are effective and commercially available for the manufacturing of polymeric and metallic dental prostheses. Although the printing of dental ceramics and composites for dental prostheses is promising, further improvements are required.